The United States Postal Service (USPS) is an independent establishment of the executive branch of the United States government (see 39 U.S.C. § 201) responsible for providing postal service in the U.S. Within the United States, it is colloquially referred to simply as "the post office."
The Board of Governors of the United States Postal Service sets policy, procedure, and postal rates for services rendered, and has a similar role to a corporate board of directors. Of the eleven members of the Board, nine are appointed by the President and confirmed by the United States Senate (see 39 U.S.C. § 202). The nine appointed members then select the United States Postmaster General, who serves as the board's tenth member, and who oversees the day to day activities of the service as Chief Executive Officer (see 39 U.S.C. § 202 and 39 U.S.C. § 203). The ten-member board then nominates a Deputy Postmaster General, who acts as Chief Operating Officer, to the eleventh and last remaining open seat.
The USPS is often mistaken for a government-owned corporation (e.g., Amtrak), but as noted above is legally defined as an "independent establishment of the executive branch of the Government of the United States," (39 U.S.C. § 201) as it is wholly owned by the government and controlled by the Presidential appointees and the Postmaster General. As a quasi-governmental agency, it has many special privileges, including sovereign immunity, eminent domain powers, powers to negotiate postal treaties with foreign nations, and an exclusive legal right to deliver first-class and third-class mail. Indeed, in 2004, the U.S. Supreme Court ruled that the USPS was not a government-owned corporation and therefore could not be sued under the Sherman Antitrust Act.
Governance and organization
The right of the United States government to engage in postal services is established by the Constitution. The USPS holds a statutory monopoly on non-urgent First Class Mail, outbound U.S. international letters
The mail monopoly is not without its critics. Nobel Prize winning economist Milton Friedman said, "there is no way to justify our present public monopoly of the post office. It may be argued that the carrying of mail is a technical monopoly and that a government monopoly is the least of evils. Along these lines, one could perhaps justify a government post office, but not the present law, which makes it illegal for anybody else to carry the mail. If the delivery of mail is a technical monopoly, no one else will be able to succeed in competition with the government. If it is not, there is no reason why the government should be engaged in it. The only way to find out is to leave other people free to enter."
Arguments against "mail monopoly"
Law enforcement agencies
The U.S. Postal Inspection Service is one of the oldest law enforcement agencies in the U.S. It was founded by Benjamin Franklin (See USPIS "Who We Are")
The mission of the USPIS is to protect the U.S. Postal Service, its employees and its customers from criminal attack, and protect the nation's mail system from criminal misuse.
U.S. law provides for the protection of mail. Postal Inspectors enforce over 200 federal laws in investigations of crimes that may adversely affect or fraudulently use the U.S. Mail, the postal system or postal employees. The USPIS is a major federal law enforcement agency.
The USPIS has the power to enforce the law by conducting search and seizure raids on entities they suspect of sending non-urgent mail through overnight delivery competitors. For example: according to the American Enterprise Institute for Public Policy Research, a private think tank (http://aei.org) the USPIS raided Equifax offices to ascertain if the mail they were sending through FedEx was truly "extremely urgent." It was found that the mail was not, and Equifax was fined $30,000 to compensate the Postal Service for the postage that was lost to FedEx.
Official website U.S. Postal Inspection Service
The USPS Office of Inspector General (OIG) of the U.S. Postal Service was authorized by law in 1996. Prior to the 1996 legislation, the Postal Inspection Service performed the duties of the OIG. The Inspector General, who is independent of postal management, is appointed by and reports directly to the nine Presidential appointed Governors of the Postal Service.
The primary purpose of the OIG is to prevent, detect and report fraud, waste and program abuse, and promote efficiency in the operations of the Postal Service . The OIG has "oversight" responsibility for all activities of the Postal Inspection Service.
Official website USPS Office of Inspector General
Although its customer service centers are called post offices in regular speech, the USPS recognizes several types of postal facilities, including the following:
A main post office (formerly known as a general post office), which is the primary postal facility in a community.  
A station or post office station, a postal facility that is not the main post office, but that is within the corporate limits of the community. 
A branch or post office branch, a postal facility that is not the main post office and that is outside the corporate limits of the community.
A classified unit, a station or branch operated by USPS employees in a facility owned or leased by the USPS.
A contract postal unit (or CPU), a station or branch operated by a contractor, typically in a store or other place of business.
A community post office (or CPO), a contract postal unit providing services in a small community in which other types of post office facilities have been discontinued.
A finance unit, a station or branch that provides window services and accepts mail, but does not provide delivery.
A processing and distribution center (P&DC, or processing and distribution facility, formerly known as a General Mail Facility), a central mail facility that processes and dispatches incoming and outgoing mail to and from a designated service area.
A sectional center facility (SCF), a P&DC for a designated geographical area defined by one or more three-digit ZIP code prefixes.
A bulk mail center (BMC), a central mail facility that processes bulk rate parcels as the hub in a hub and spoke network.
An auxiliary sorting facility (ASF), a central mail facility that processes bulk rate parcels as spokes in a hub and spoke network. Types of postal facilities
In February, 2006, the USPS announced that they plan to replace the nine existing facility-types with five processing facility-types:
Over a period of years, these facilities are expected to replace Processing & Distribution Centers, Customer Service Facilities, Bulk Mail Centers, Logistic and Distribution Centers, annexes, the Hub and Spoke Program, Air Mail Centers, Remote Encoding Centers, and International Service Centers.
The changes are a result of the declining volumes of single-piece first-class mail, population shifts, the increase in drop shipments by advertising mailers at destinating postal facilities, advancements in equipment and technology, redundancies in the existing network, and the need for operational flexibility
While common usage refers to all types of postal facilities as "substations," the USPS Glossary of Postal Terms does not define or even list that word.
Temporary stations are often set up for applying pictorial cancellations.
Regional Distribution Centers (RDCs), which will process all classes of parcels and bundles and serve as Surface Transfer Centers;
Local Processing Centers (LPCs), which will process single-piece letters and flats and cancel mail;
Destination Processing Centers (DPC), sort the mail for individual mail carriers;
Airport Transfer Centers (ATCs), which will serve as transfer points only; and
Remote Encoding Centers (RECs). Evolutionary Network Development (END) program
For any letter addressed within the United States, the USPS requires two pieces of information on the envelope.
A third, and optional (but strongly suggested) addition is a return address. This is the address that the recipient may respond to, and, if necessary, the letter can be returned to if delivery fails. It is usually placed in the upper-left corner or occasionally on the back (though the latter is standard in some countries). Undeliverable mails that cannot be readily returned, including those without return addresses, are treated as dead mails at a Mail Recovery Center in Atlanta, Georgia or Saint Paul, Minnesota.
Line 1: Name of recipient
Line 2: Street address or P.O. Box
Line 3: City State (ISO 3166-2:US code or APO/FPO code) and ZIP+4 code
MR JEFF GILBERT
1111 JOHNSON ST
NEW YORK NY 10036-4658
The USPS maintains a list of proper abbreviations.
The city and state designations are a redundant safety measure used in the case that the printed ZIP code is illegible or ambiguously written. Since the ZIP code system is such that there is only one street of any name for any ZIP code (ex. there is only one Johnson Street in the 10036 ZIP area), it is possible to exclude the city and state from a mailing label and still have the package delivered, assuming the label is legible.
The formatting of a return address is identical. A common myth is that a comma is required after the city name, but this is not true. (Some style manuals do recommend using the comma when typesetting addresses in other contexts, however.) The Post Office recommends use of all upper case block letters using the appropriate formats and abbreviations and leaving out all punctuation except for the hyphen in the ZIP+4 code to ease automated address reading and speed processing, particularly for handwritten addresses; if the address is unusually formatted or illegible enough, it will require hand-processing, delaying that particular item. The USPS publishes the entirety of their postal addressing standards.
Address of the recipient: Placed on the front (non opening) side of the envelope in the center. Generally, the name of the addressee should be included above the address itself. Additionally, a ZIP+4 code is not necessary.
Postage indication: All parcels must include an indication that postage has been paid. In most cases, this is a stamp, though metered labels are also common. Members of the U.S. Congress, among others, have franking privileges, which only require a signature.
- First-class mail costs 41¢ upwards, depending on the weight and dimensions of the letter and the class, and the indicia is supposed to be placed in the upper-right corner. Addressing envelopes
Processing of standard sized envelopes and cards is highly automated, including reading of handwritten addresses. Mail from individual customers and public postboxes is collected by mail carriers into plastic tubs. The tubs are taken to a Processing and Distribution Center and emptied into hampers which are then automatically dumped into a Dual Pass Rough Cull System (DPRCS). As mail travels through the DPRCS, large items, such as packages and mail bundles, are removed from the stream. As the remaining mail enters the first machine for processing standard mail, the Advanced Facer-Canceler System (AFCS), pieces that passed through the DPRCS but do not conform to physical dimensions for processing in the AFCS (i.e. large envelopes or overstuffed standard envelopes) are automatically diverted from the stream. Mail removed from the DPRCS and AFCS is manually processed or sent to parcel sorting machines.
In contrast to the previous system, which merely canceled and postmarked the upper right corner of the envelope, thereby missing any stamps which were inappropriately placed, the AFCS locates indicia (stamp or metered postage mark), regardless of the orientation of the mail as it enters the machine, and cancels it by applying a postmark. Detection of indicia enables the AFCS to determine the orientation of each mailpiece and sort it accordingly, rotating pieces as necessary so all mail is sorted right-side up and faced in the same direction in each output bin. Mail is output by the machine into three categories: mail already affixed with a bar code and addressed (such as business reply envelopes and cards), mail with machine printed (typed) addresses, and mail with handwritten addresses. Additionally, machines with a recent Optical Character Recognition (OCR) upgrade have the capability to read the address information, including handwritten, and sort the mail based on local or outgoing ZIP codes.
Mail with typed addresses goes to a Multiline Optical Character Reader (MLOCR) which reads the ZIP Code and address information and prints the appropriate bar code onto the envelope. Mail (actually the scanned image of the mail) with handwritten addresses (and machine-printed ones that aren't easily recognized) goes to the Remote Bar Coding System, a highly advanced scanning system with a state of the art neural net processor which is highly effective at correctly reading almost all addresses, no matter how poorly written . It also corrects spelling errors and, where there is an error, omission, or conflict in the written address, identifies the most likely correct address. When it has decided on a correct address, it prints the appropriate bar code onto the envelopes, similarly to the MLOCR system. RBCS also has facilities in place, called Remote Encoding Centers, that have humans look at images of mail pieces and enter the address data. The address data is associated with the image via an ID Tag, a fluorescent Barcode printed by mail processing equipment on the back of mail pieces.
If a customer has filed a change of address card and his or her mail is detected in the mailstream with the old address, the mailpiece is sent to a machine that automatically connects to a Computerized Forwarding System database to determine the new address. If this address is found, the machine will paste a label over the former address with the current address. The mail is returned to the mailstream to forward to the new location.
Mail with addresses that cannot be resolved by the automated system are separated for human intervention. If a local postal worker can read the address, he or she manually sorts it out according to the zip code on the article. If the address cannot be read, mail is either returned to the sender (first class mail with a valid return address) or is sent to one of three Mail Recovery Centers in the United States (formerly known as Dead Letter Offices, originated by Benjamin Franklin in the 1770s) where it receives more intense scrutiny, including being opened to determine if any of the contents are a clue. If no valid address can be determined, the items are held for 90 days in case of inquiry by the customer; and if they are not claimed then they are either destroyed or auctioned off at the annual Postal Service Unclaimed Parcel auction to raise money for the service.
Once the mail is bar coded, it is automatically sorted by a Delivery Bar Code System that reads the bar code and determines the destination of the mailpiece to postal stations. Items for local delivery are retained in the postal station while other items are trucked to either the appropriate station if it is within approximately 200 miles, or the airport for transport to more distant destinations. Mail is flown, usually as baggage on commercial airlines, to the airport nearest the destination station, then at a nearby processing center the mail is once again read by a Delivery Bar Code System which sorts the items into their local destinations, including grouping them by individual mail carrier. After the September 11, 2001 attacks, only letter-sized mail has been flown on passenger airlines. Packages are solely transported via cargo carriers, most notably FedEx.
The U.S. Postal Service announced changes to the classes of domestic mail and select postage rate increases effective July 1, 1996. Rates for single-piece first-class, single-piece Standard Mail (formerly third- and fourth-class), and international mail classes did not change. The following general description of each new mail class and the enclosed rate scales are provided for your information in determining postage costs for all mailings made on or after July 1, 1996.
U.S. Mail is delivered Monday through Saturday, with the exception of observed federal holidays.
Major products and services
First-class mail was retained in the 1996 restructuring, but divided into two new mail subclasses: Automation and Nonautomation.
In 2007, First-Class Mail rates were restructured again, this time with rates based on shape along with weight.
The Automation mail subclass must be 100-percent delivery point barcoded and certified every six months for addressing and presort accuracy.
The Nonautomation mail subclass is the same as the previous first-class. However, bulk mailers are now required to certify the accuracy of the five-digit ZIP Codes at least once a year, and the customer address mail list must be updated at least every six months.
Cards/Letters: Least changed. A card must be between 5" x 3.5" x .007" and 6" x 4.25" x .016" and is charged 26 cents. An envelope must be between 5" x 3.5" x .007" and 11.5" x 6.125" x .25". This rate is 41 cents for the first ounce and 17 cents for each ounce above that, up to 3.5 ounces. If any of these dimensions are above these, the mailpiece goes to the next higher rate, Large Envelope (Flats)
Large Envelope or Flat: If a mailpiece is too big for Letter Rate, it goes up to this rate. The maximum dimensions of this are 15" x 12" x .75" and is charged 80 cents for the first ounce and 17 cents for every ounce above that up to 13 ounces. If any one of the dimensions are exceeded for Large Envelope, or are too rigid, nonrectangular/square, or not uniformely thick must use parcel rates.
Packages or Parcels: If a mailpiece is too large for Large Envelope rate, it goes up to this rate. The length + girth must not exceed 108 inches, and weight must not exceed 13 ounces. The rate for this level is $1.13 for the first ounce and 17 cents for every ounce thereafter. First-class mail
Restructured from Second-Class Mail in 1996, the Periodicals class in general retains the same mailing requirements except for more stringent requirements to qualify for the automation rates. If the mail piece does not qualify for automation rates, the mailer must use the more expensive nonautomation rates for respective sorting levels. Mailers must change the second-class endorsement to Periodicals by July 1, 1996, in order to comply with reform requirements.
Restructured from Third-Class Mail and Fourth-Class Mail in 1996, and used mainly for businesses, Standard Mail has these requirements:
Third- and fourth-class mail was restructured in 1996 into Standard Mail (A) and Standard Mail (B):
Standard Mail (A) consists of three new mail subclasses: Automation, Enhanced Carrier Route, and Regular. The minimum bulk mailing requirement of 200 addressed pieces or 50 pounds of addressed pieces remains the same as under previous third-class mail rules, but now requires mail list certification.
Standard Mail (B) consists of the following mail subclasses: Parcel Post, Bound Printed Matter, Special Standard Mail, Library Mail, and Nonprofit. The latter two subclasses are not authorized for government use. The mailing requirements for this mail class remain unchanged from fourth-class mail. However, the mail piece must bear the sender's return address, and the delivery address must include the correct ZIP Code. Special fourth-class mail was renamed Special Standard Mail, and the basic requirements for its use remain the same. 
Minimum 200 pieces per mailing
Must weigh less than 1 lb (454 g)
No return service unless requested (an additional fee is charged for return service)
Not for personal correspondence, letters, bills, or statements
The Automation mail subclass must be 100-percent delivery point barcoded (11 digits) for letters. The ZIP+4 barcode is acceptable for flats. The carrier routes and coding accuracy for barcoded addresses must be certified quarterly and semi-annually, respectively.
The Enhanced Carrier Route mail subclass requires that the basic carrier route be in a line of travel sequence and that the high density and saturation rate mail be in walk sequence to qualify for the respective rates.
The Regular mail subclass must be certified annually for five-digit ZIP Code accuracy. Standard Mail
Used for businesses to send large quantities of mail.
Can be First-Class Mail, Standard Mail, Bound Printed Matter, Media Mail, or Parcel Post
Annual fee required (For each mail class used)
Enforced rules about mailpiece quality, address format, and address quality.
May require additional work by the sender, such as certified address matching and pre-sorting by ZIP Code or walk sequence.
Mail must usually be brought to a Bulk Mail Entry Unit post office. Bulk Mail
Used to send packages weighing up to 70 pounds (31.75 kg)
Delivery standards are 2–9 business days except to Alaska and Hawaii, where container ships carry mail and may take as long as five weeks
Rates based on distance, weight, and shape
Delivery to every address in the United States, including PO Boxes and Military Addresses. Media Mail
Same as Media Mail, but receives an additional discount and may be used only for books or recordings being sent to or from a public library, museum, or academic institution.
Same as Media Mail but it is used to mail permanently-bound sheets of advertising, promotional, directory or editorial material such as catalogs and phonebooks. It may be slightly cheaper than Media Mail rates. Observations:
Package can weigh up to 15 lb.
Sheets must be permanently-bound by secure fastenings such as staples, spiral binding, glue or stitching.
At least 90% of the sheets must be imprinted by any process other than handwriting or typewriting.
Mail must be marked "return service required" to receive undeliverable back. Mail without this marking will be disposed of.
Postage may be applied by PC postage, permit imprint, or stamps, but cannot be bought at a retail counter, effective May 14, 2007. Bound Printed Matter
Priority Mail is an expedited mail service with a few additional features.
Average delivery time is 2–3 days, (not guaranteed)
Flat rate envelopes and boxes available (one rate for whatever you put in the envelope, though the envelope's seal must be the primary method of enclosure) 
Packages up to 70 pounds (31.75 kg).
Label can be printed online
Delivery to any address in the United States
Dimensional weight is used along with actual weight for all parcels above 1 cubic foot. Priority Mail
According to the USPS's Domestic Mail Manual, Registered Mail is "the most secure service that the USPS offers" and is used to send (often in combination with insurance) high-value items such as jewelry or coins, sensitive or irreplaceable paperwork, and DoD classified information up to the SECRET level. Items sent via Registered mail are tracked via a system of receipts as they move through the mail system, and they can be tracked electronically by the sender via phone or through the USPS's web site. Items sent via Registered mail are transported to the Processing and Distribution Center in a sealed container, and once there are kept separate from all other mail in a location with secure access. Every time the item is handled, this is noted in a ledger.
Delivery time is about the same or longer than First Class, and is not guaranteed
Parcels or letters must meet the mailing standards for First Class mail, including minimum size
Must be presented to a clerk in person at a Post Office, cannot be put into an on-street box or rural pickup box
Cannot be Business Reply Mail
Packages must be brown-paper wrapped (often done for the customer) Registered Mail
Express Mail is the fastest mail service.
Typically overnight or second-day delivery
Delivery to most, but not all, US locations 365 days a year
Flat rate envelope available
Packages up to 70 pounds (31.75 kg)
Delivery to most addresses in the United States
Guaranteed on-time delivery or the postage is refunded subject to conditions Express Mail
Provide a safe alternative to sending cash through the mail
Money orders are cashable only by the recipient, just like a bank check. One of the reasons for the growing popularity of money orders is that, unlike a personal bank check, they are pre-paid and therefore cannot bounce. Postal money orders
Airmail (Letter Post), Global Priority, Global Express, and Global Express Guaranteed Mail are offered to ship mail and packages to almost every country and territory on the globe. Ironically, much of this service is provided by FedEx.  On May 14, 2007, the United States Postal Service canceled all outgoing international surface mail (sometimes known as "sea mail") from the United States, citing increased costs and reduced demand due to competition from airmail services such as FedEx and UPS.  The decision has been criticized by the Peace Corps and military personnel overseas, as well as independent booksellers and other small businesses who rely on international deliveries.
The United States Postal Service does not directly own or operate any aircraft or trains. The mail and packages are flown on airlines with which the Postal Service has a contractual agreement. The contracts change periodically. Depending on the contract, aircraft may be painted with the USPS paint scheme. Contract airlines have included: Emery Worldwide, Ryan International Airlines, FedEx, Rhoades Aviation, and Express One International. The Postal Service also contracts with Amtrak to carry some mail between certain cities such as Chicago and Minneapolis-St. Paul.
Airline and rail division
Until 1912, mail was delivered 7 days a week. As the postal service grew in popularity and usage in the 1800s, local religious leaders were noticing a decline in Sunday morning church attendance due to local post offices doubling as gathering places. These leaders appealed to the government to intervene and close post offices on Sundays.
This is a matter of some controversy. Many believe that the post office is closed to prevent a government subsidized agency from forcing Christians to work on Sunday, a protection of religious freedom. Others believe the government used its power to take "competition" away from churches, and point out that Christians and those of any other belief work for the post office voluntarily (and that no exemption has been put in place for the holy days of other faiths); therefore, it is seen by some as a violation of separation of church and state.
As a result of this intervention by the government, U.S. Mail (with the exception of Express Mail) is not delivered on Sunday, with the exception of a few towns in which the local religion has had an effect on the policy. U.S. Mail is delivered Monday through Saturday, with the exception of observed federal holidays.
Sunday mail delivery
The Postal Service offers additional services for some types of mail.
Confirms delivery with signature
Recipient's first initial and last name is typographically displayed online
Recipient's signature is kept on file
Only available with First Class Mail parcels, Priority Mail, and Package Services (Media Mail, Parcel Post, and Bound Printed Matter) Signature confirmation
Provides package with insurance from loss or damage while in transit
Available for amounts up to $5,000
Covers material losses only minus depreciation Insurance
Provides proof of mailing, and a delivery record
Available for First Class Mail and Priority Mail
Available for sending U.S. Government classified information, up to the CONFIDENTIAL level. Certified Mail
Allows merchants to offer customers an option to pay upon delivery
Insurance comes included with fee
Amount to be collected cannot exceed $1,000
Available for First-Class Mail, Express Mail, Priority Mail, and Package Services (Parcel Post, Bound Printed Matter, and Media Mail). Collect On Delivery (C.O.D.)
In 2006 the Postal Service registered traditional trademarks Pony Express and Air Mail.
Air Mail and Pony Express trademarks
All unused U.S. postage stamps issued since 1861 are still valid as postage at their indicated value. Stamps with no value shown or denominated by a letter are also still valid at their purchase price.
The cost of mailing a letter increased to 39 cents in 2006, but the Post Office now offers a "forever" stamp. This stamp will be sold at the standard rate, but will always be valid for 1st class mail, no matter how rates rise in the future.
All U.S. postage stamps and other postage items that were released before 1978 are in the public domain. The postal service holds copyright to such materials released after 1978 under Title 17 of the United States Code. Written permission is required for use of copyrighted postage stamp images. 
Copyright and reproduction
See also Postage meter
In addition to using standard stamps, postage can now be printed from a personal computer using a system called Information Based Indicia. Authorized providers of PC Postage are:
Endicia Internet Postage
Click-N-Ship PC postage
Customers can also use their own pictures or images to print their very own customized postage products using one of the vendors listed below. Customized postage is valid U.S. postage and can be used just like a stamp. Customized postage can be ordered in all first-class rates, as well as in the Priority Mail rate.
Stamps.com Customized postage
In addition to the USPS Click-N-Ship service, the USPS has partnered with other companies such as Pitney Bowes which allows PayPal to offer postage label printing with the services the site has to offer. In PayPal's case, a user can print postage on PayPal and have the costs deducted from their PayPal account or a linked bank account. The seller may then drop off the parcel at a location accepting parcels or request pick-up at the address of origin.
Affiliation with Online Postage Providers
Beginning in 1996, the USPS was head sponsor of a professional cycling team bearing its name. The team featured Lance Armstrong, seven-time winner of the Tour de France. The sponsorship ended in 2004, when the Discovery Channel stepped in as the main sponsor and renamed the team as the Discovery Channel Pro Cycling Team.
The USPS employs more people than any company in the United States except Wal-Mart. It employed 790,000 personnel in 2003, divided into offices, processing centers, and actual post offices. USPS employees are divided into three major crafts according to the work they engage in:
Other positions outside the main three crafts include:
Though USPS employs many individuals, as more Americans send information via electronic mail, fewer postal workers are needed to work dwindling amounts of mail. Post offices and mail facilities are constantly downsizing, replacing craft positions with new machines and elimating mail routes. Thus, postal hiring has been criticized as sporadic. Competition for new, full-time, salaried positions can be highly intense.
Letter Carriers, also referred to as mailmen or mail-carriers; are the public face of the USPS. As the front line, carriers are routinely pressured to move faster, work harder, and perform more tasks in a timed manner. The most stressful of crafts, carriers are watched, timed and inspected more than any other employees.
Mail handlers and processors often work in the evening and night to prepare mail and bulk goods for the carriers to deliver. Work is physically strenuous, especially for mail handlers; many mailbags loaded from and onto trucks weigh as much as 70 pounds (32 kg).
Clerks sort and/ or case first and second class mail as well as standard and bulk rate mail. Clerks also work in the post offices, handling customer needs, receiving express mail, and selling stamps.
DCOs (Data Conversion Operators), who type out address information and forward mail to their destinations.
Maintence and Custodians, who see to the overall operation and cleaning of mail sorting machines, work areas, public parking and genreal facility operations.
Casuals and TEs (Temporary Employees), who are hired in seasonal intervals as part-time workers with lower wages, no benefits, and can often work up to 12hrs a day, 7 days a week if needed. Employment in the USPS
As violent ("Going Postal")
In the early 1990s, there was a widely publicized wave of workplace shootings by disgruntled employees at USPS facilities, which led to a postal regulation that prohibits the possession of firearms in all postal facilities. Due to media coverage, postal employees gained a reputation among the general public as being mentally ill. The USPS Commission on a Safe and Secure Workplace found that "Postal workers are only a third as likely as those in the national workforce to be victims of homicide at work." This stereotype in turn has influenced American culture, as seen in the slang term "going postal" (see Patrick Sherrill for information on his August 20, 1986, rampage) and the computer game Postal. Also, in the opening sequence of Naked Gun 33⅓: The Final Insult, a yell of "Disgruntled postal workers" is heard, followed by the arrival of postal workers with machine guns. In an episode of Seinfeld, the character Newman, who is a mailman, explained in a dramatic monologue that postal workers "go crazy and kill everyone" because the mail never stops.
The Setting the Record Straight section of USPS.com features letters to newspaper editors, television producers, and other media representatives which USPS has sent in response to criticism of the Postal Service and to uses of the term "going postal."
Lines supposedly from the Ancient Greek historian Herodotus, "Neither snow nor rain nor heat nor gloom of night stays these couriers from the swift completion of their appointed rounds," are engraved on the exterior of the U.S. Postal Service building in New York City; they are often erroneously cited as the official motto of the USPS. The translation may be a slightly more poetical rendition of the original text, though the same sentiment is expressed.
The postman in the animated television program Garfield and Friends is so dedicated to delivering mail past Garfield's elaborate traps that he attempts to deliver the mail in a tank. He professes a simple love of being greeted as he delivers the mail.
On the popular television show Cheers, Cliff Clavin has portrayed himself as a dedicated postal worker on many occasions. The misconception of postal workers always drinking led to new postal regulations that made drinking in a bar while in uniform a fireable offense.
In Lucifer's Hammer a dedicated postal worker goes about his rounds even though a comet has just hit the earth.
In The Postman the titular character catalyzes a rebirth of civilization by donning the uniform and pretending to be a letter carrier from a post-apocalyptic United States government.
In contrast, on the popular television program Seinfeld, Jerry's neighbor Newman, a letter carrier, refused to deliver mail when it rained. This is much to the dismay of George Costanza, who is unable to remember the whole of the quotation but does point out to Newman that rain is the first weather phenomena mentioned.
As dedicated (Neither snow nor rain nor heat nor gloom of night...)
In the 1947 classic, Miracle on 34th Street, the identity of Kris Kringle (played by Edmund Gwenn), as the one and only "Santa Claus" was validated by a Federal Court, based on the delivery of 21 bags of mail (famously carried into the courtroom) to the character in question. The contention was that it would have been illegal for the United States Post Office to deliver mail that was addressed to "Santa Claus" to the character "Chris Kringle", unless he was, in fact, the one and only Santa Claus. Judge Henry X. Harper (played by Gene Lockhart), ruled that since the US Government had demonstrated (through the delivery of the bags of mail) that Kris Kringle was Santa Claus, then the State of New York did not have the authority to overrule that decision.
In promoting the issuance of a new stamp series based on the Star Wars films, the United States Postal Service is decorating many of their mail collection boxes in some 200 cities to look like R2-D2. 
In the 1996 movie Jingle All The Way, Arnold Schwarzenegger stars as a father competing against a deranged postal worker (played by Sinbad), as well as con-artist Santas, the police, and almost every parent in town, to get his son a cherished Turbo Man toy. Sinbad regularly resorts to fighting, tricks, and threats of going postal to achieve his goal.
Film directors John Singleton and Keenan Ivory Wayans have both had director cameos in a number of films as letter carriers. Singleton also wrote and directed the 1993 film Poetic Justice about a hairdresser (played by Janet Jackson) who falls in love with a mail carrier (played by the late Tupac Shakur) on an overnight delivery run.
In the novel Going Postal, by Terry Pratchett, the motto of the Ankh Morpork Post Office is "Neither rain nor snow nor gloom of night can stay these messengers about their duty." which is very similar to the United States Postal Service motto. In the Movies
United States postal abbreviations
History of USPS rates
Rural delivery service
Rural Letter Carrier
United States Postal Service creed
United States Postal Inspection Service
Postage stamps and postal history of the United States of America
List of available US stamp denominations
U.S. Postal Exams
Canada Post - Postes Canada
Royal Mail - The U.K. equivalent to the USPS
Philately (Stamp collecting) See also
American Postal Workers Union *APWU Official website
National Association of Letter Carriers *NALC Official website
National Postal Mail Handlers Union *NPMHU Official website
National Rural Letter Carriers Association *NRLCA Official website
National Association of Postmasters *NAPUS Official website
National Association of Postal Supervisors *NAPS Official website
National League of Postmasters *Official website Gallery of USPS post offices
U.S. Post Box in front of the Post Office in Conneaut, Ohio
"Snorkel" mailboxes configured for drive-through access in Los Altos, California
A R2-D2-themed mailbox in Boston, Massachusetts as part of the USPS celebration of Star Wars' 30th anniversary