A History of Postal Codes!

I was reading my 1958 Old Farmers Amanac by Robert B. Thomas (who is, of course, long dead, but still has his name on the front cover of every single one of these, all 215. Well, maybe it is 216, now. The 2008 Almanac came out in September. They have for a long time, too. That is not a recent change to the Almanac.

What struck me was the adverts in it. Inside where all these cheesy adverts with weird drawings that are so hallmark of the 50s and the addresses were there. They all looked like this:

Joseph Harris Co.

295 Moreston Farm

Rochester 11, N.Y.

Anything look strange about that address? Like the postal code is part of the town name, and not five to nine digits. I knew that the postal code system was not always in place, but I did not realise that as late as 1958 it wasn't in place! 1963, same thing - Chicago 10, Ill. 1964, 1966, ah-ha! 1967 - the addresses look like this:

Alonzo O. Bliss Medical Co.

Washington, D.C. 20013

Most states seemed to have adopted this system, but there is a California address in there that still goes by the older system: Oakland 4, CA. So some time in mid- to late 1966 this system was officially put into effect. Let's see how close I am:

From Wikipedia:

A postal code (known in various countries as a post code, postcode, or ZIP code) is a series of letters and/or digits appended to a postal address for the purpose of sorting mail.

Germany was the first country to introduce a postal code system, in 1941. The United Kingdom followed in 1959 and the United States in 1963.

In February 2005, 117 of the 190 member countries of the Universal Postal Union had postal code systems. Examples of countries that do not have national systems include Ireland, Hong Kong, Panama and Vietnam.

Although postal codes are usually assigned to geographical areas, special codes are sometimes assigned to individual addresses or to institutions that receive large volumes of mail, such as government agencies and large commercial companies. One example is the French Cedex system.

Postal zone numbers
Before postal codes as described here were used, large cities were often divided into postal zones or postal districts, usually numbered from 1 upwards within each city. The newer postal code systems often incorporate the old zone numbers, as with London postal district numbers, for example. Ireland, still uses postal district numbers in Dublin. In New Zealand, Auckland, Wellington and Christchurch were divided into postal zones, but these fell into disuse, and have now become redundant as a result of a new postcode system being introduced.

Note: In Wikipedia, "postal codes" gives information about all countries. If you look up "zip codes", you get the United States postal code information only because no other country had a system called ZIP. (See below...)

The ZIP code is the system of postal codes used by the United States Postal Service (USPS). The letters ZIP, an acronym for Zone Improvement Plan, are written properly in capital letters and were chosen to suggest that the mail travels more efficiently, and therefore more quickly, when senders use it. The basic format consists of five numerical digits. An extended ZIP + 4 code includes the five digits of the ZIP code, a hyphen and then four more digits, which allow a piece of mail to be directed to a more precise location than by the ZIP code alone. ZIP Code was originally registered as a trademark by the U.S. Postal Service but its registration has since expired.

Background
The postal service implemented postal zones for large cities in 1943. For example:

Mr. John Smith
3256 Epiphenomenal Avenue
Minneapolis 16, Minnesota

Wikimedia Foundation Inc.
200 2nd Ave. South #358
St. Petersburg 1, Florida

The "16" in the first example and "1" in the second is the number of the postal zone within the city.

By the early 1960s a more general system was needed, and on July 1, 1963, non-mandatory ZIP codes were announced for the whole country. Robert Moon, an employee of the post office, is considered the father of the ZIP code. He submitted his proposal in 1944 while working as a postal inspector.

The post office only gives credit to Moon for the first three digits of the ZIP code, which describe the region of the country. In most cases, the last two digits coincide with the older postal zone number, thus:

Mr. John Smith
3256 Epiphenomenal Avenue
Minneapolis, Minnesota 55416

Wikimedia Foundation Inc.
200 2nd Ave. South #358
St. Petersburg, Florida 33701

In 1967, these were made mandatory for second- and third-class bulk mailers, and the system was soon adopted generally. The United States Post Office used a cartoon character, Mr. ZIP, to promote use of the ZIP code. He was often depicted with a legend such as "USE ZIP CODES" in the selvage of panes of stamps or on labels contained in, or the covers of, booklet panes of stamps. Curiously enough, the only time the Postal Service issued a stamp promoting the ZIP code, in 1974, Mr. ZIP was not depicted.

ZIP + 4
In 1983, the U.S. Postal Service began using an expanded ZIP code system called "ZIP + 4", often called "plus-four codes" or "add-on codes."

Wikimedia Foundation Inc.
200 2nd Ave. South #358
St. Petersburg, FL 33701-4313

Furthermore, recently the Postal Service started a "Find a ZIP Code" feature on its website, which provides an address format that is most compatible with its optical character recognition, or OCR, scanners:

Structure and allocation

By geography
ZIP codes are numbered with the first digit representing a certain group of U.S. states, the second and third digits together representing a region in that group (or perhaps a large city) and the fourth and fifth digits representing a group of delivery addresses within that region. The main town in a region (if applicable) often gets the first ZIP codes for that region; afterward, the numerical order often follows the alphabetical order.

Generally, the first three digits designate a sectional center facility, the mail-sorting and -distribution center for an area. A sectional center facility may have more than one three-digit code assigned to it. For example, the Northern Virginia sectional center facility in Merrifield is assigned codes 220, 221, 222 and 223. In some cases, a sectional center facility may serve an area in an adjacent state, usually due to the lack of an appropriate location for a center in that region. For example, 739 in Oklahoma is assigned to Liberal, Kansas; 865 in Arizona is assigned to Gallup, New Mexico; and 961 in California to Reno, Nevada.

Geographically, many of the lowest ZIP codes are in the New England region, since these begin with '0'. Also in the '0' region are Puerto Rico, the U.S. Virgin Islands and APO/FPO military addresses for personnel stationed in Europe. The lowest ZIP code is in Holtsville, New York (00501, a ZIP Code exclusively for the U.S. Internal Revenue Service center there). Other low ZIP codes are 00601 for Adjuntas, Puerto Rico; 01001 for Agawam, Massachusetts, and 01002 for Amherst, Massachusetts. Up until 2001 there were also six zip codes even lower than 00501 that were numbered from 00210 to 00215 (located in Portsmouth, New Hampshire) and were used by the Diversity Immigrant Visa program to receive applications from non-US citizens.

The numbers increase southward along the East Coast, such as 02115 (Boston), 10001 (New York City), 19103 (Philadelphia), 20008 (Washington, D.C.), 30303 (Atlanta) and 33130 (Miami) (these are only examples as each of these cities contain several zip codes in the same range). From there, the numbers increase heading westward and northward. For example, 40202 is in Louisville, 50309 in Des Moines, Iowa, 60601 in Chicago, 77063 in Houston, 80202 in Denver, 94111 in San Francisco, 98101 in Seattle, and 99950 in Ketchikan, Alaska.

The first digit of the ZIP code is allocated as follows:

0 = Connecticut (CT), Massachusetts (MA), Maine (ME), New Hampshire (NH), New Jersey (NJ), Puerto Rico (PR), Rhode Island (RI), Vermont (VT), Virgin Islands (VI), APO Europe (AE), FPO Europe (AE)

1 = Delaware (DE), New York (NY), Pennsylvania (PA)

2 = District of Columbia (DC), Maryland (MD), North Carolina (NC), South Carolina (SC), Virginia (VA), West Virginia (WV)

3 = Alabama (AL), Florida (FL), Georgia (GA), Mississippi (MS), Tennessee (TN), APO Americas (AA), FPO Americas (AA)

4 = Indiana (IN), Kentucky (KY), Michigan (MI), Ohio (OH)

5 = Iowa (IA), Minnesota (MN), Montana (MT), North Dakota (ND), South Dakota (SD), Wisconsin (WI)

6 = Illinois (IL), Kansas (KS), Missouri (MO), Nebraska (NE)

7 = Arkansas (AR), Louisiana (LA), Oklahoma (OK), Texas (TX)

8 = Arizona (AZ), Colorado (CO), Idaho (ID), New Mexico (NM), Nevada (NV), Utah (UT), Wyoming (WY)

9 = Alaska (AK), American Samoa (AS), California (CA), Guam (GU), Hawaii (HI), Marshall Islands (MH), Federated States of Micronesia (FM), Northern Mariana Islands (MP), Oregon (OR), Palau (PW), Washington (WA), APO Pacific (AP), FPO Pacific (AP)

The next two digits represent the sectional center facility (e.g. 432xx = Columbus OH), and the fourth and fifth digits represents the area of the city (if in a metropolitan area), or a village/town (outside metro areas): 43209 (4=Ohio, 32=Columbus, 09=Bexley). When a sectional center facility's area crosses state lines, that facility is assigned separate three-digit prefixes for the states that it serves; thus, it is possible to identify the state associated with any ZIP Code just by looking at the first three digits.

Despite the geographic derivation of most ZIP codes, the codes themselves do not represent geographic regions; they generally correspond to address groups or delivery routes. Consequently, ZIP Code "areas" can overlap, be subsets of each other, or be artificial constructs with no geographic area. Similarly, in areas without regular postal routes (rural route areas) or no mail delivery (undeveloped areas), ZIP Codes are not assigned or are based on sparse delivery routes, and hence the boundary between ZIP code areas is undefined.

For example, U.S. government agencies in and around the nation's capital are assigned ZIP codes starting with 20200 to 20599, which are Washington, D.C., ZIP codes, even if they are not located in Washington itself. While the White House itself is located in ZIP code 20006, it has the ZIP code 20500. The Nuclear Regulatory Commission is located in Rockville, Maryland, at ZIP code 20852, but has been assigned by the Postal Service the address "Washington, DC 20555". The United States Patent and Trademark Office used to be located in Crystal City, Virginia at ZIP Code 22202 but was assigned by the Postal Service the address "Washington, DC 20231"; however, since its move to Alexandria, Virginia, it uses the ZIP + 4 code 22313-1450.

Rarely, a locality is assigned a ZIP code that does not match the rest of the state. This is when the locality is so isolated that it is served from a sectional center in another state. For example, Fishers Island, New York, bears the ZIP code 06390 and is served from Connecticut — all other New York ZIP codes (excepting those at Holtsville for the IRS) begin with "1". Similarly, some Texas ZIP codes are served from New Mexico and thus bear codes beginning with "8" rather than "7". Returned government parcels from the District of Columbia are sent to ZIP codes beginning with "569", so that returned parcels are security checked at a remote facility (this was put into place after the anthrax scare).

ZIP codes only loosely tied to cities
An address's ZIP code and the "city" name written on the same line do not necessarily mean that that address is within that city. The Postal Service designates a single "default" place name for each ZIP code. This may be an actual incorporated town or city, a subentity of a town or city or an unincorporated census-designated place. Additional place names, also of any of these types, may be recognized as "acceptable" for a certain ZIP code. Still others are deemed "not acceptable", and if used may result in a delay in mail delivery.

Default place names are typically the actual city or town that the address is located in. However, for many cities that have incorporated since ZIP codes were introduced the actual city name is only "acceptable" and not the "default" place name. Many databases automatically assign the "default" place name for a ZIP code, without regard to any "acceptable" place names. For example, Centennial, Colorado is divided among seven ZIP codes assigned to "Aurora", "Englewood" or "Littleton" as its "default" place names. Thus, from the perspective of the U.S. Postal Service, the city of Centennial and its 100,000 residents do not exist - they are part of Aurora, Englewood or Littleton. In the ZIP-code directory, Centennial addresses are listed under those three cities. And since it is "acceptable" to write "Centennial" in conjunction with any of the seven ZIP codes, one can write "Centennial" in an address that is actually in Aurora, Englewood, or Littleton, as long as it is in one of the shared ZIP Codes.

"Acceptable" place names are often added to a ZIP code in cases where the ZIP-code boundaries divide them between two or more cities, as in the case of Centennial. However, in many cases only the "default" name can be used, even when many addresses in the ZIP code are in another city. For example, approximately 85% of the area served by the ZIP code 85254, to which the place name "Scottsdale, Arizona," is assigned, is actually inside the city limits of neighboring Phoenix. This is because the post office that serves this area is in Scottsdale. This has led some residents of the ZIP code to believe that they live in Scottsdale when they actually live in Phoenix. A Scottsdale website listing the positive and negative aspects of the city mentioned the 85254 ZIP code as a positive aspect because "Scottsdale" is being used for businesses located outside the Scottsdale city limits.

This phenomenon is repeated across the country. The previously mentioned Englewood is a land-locked, inner-ring suburb that was built out by the 1960s. Its post office served the area that is now the high-growth southern tier of the Denver metropolitan area, and ZIP codes in this area were assigned "Englewood" as their "default" place name. An employment center as large as downtown Denver has grown in this area, and its office parks are the headquarters for many internationally recognized corporations. Even though they are actually located in other cities, they indicate "Englewood" as their location, as this is the "default" postal place name. As a result, there are really two "Englewoods" — the actual city, small and with a largely working-class residential population, and, a number of miles away, the postal "Englewood," a vast suburban area of upscale subdivisions and office parks that have nothing to do with the City of Englewood yet share a split identity with it solely because of ZIP codes. People who say that they live or work in "Englewood" and identify closely with it may rarely enter the actual city of that name. In Indiana the zip code for a town usually indicates the zip code for its corresponding township as nearly all of Indiana's small town post offices have rural routes.

"Acceptable place names" also come into play in areas of the country where many citizens identify more strongly with a particular urban center than the municipality they actually live in. For example, Allegheny County, Pennsylvania has 130 distinct municipalities, but many of the county's residents, and even some residents of adjacent counties, commonly use "Pittsburgh, PA" as their postal address. The same thing applies in many cities that have more than one zip code, like Evansville, Indiana or Jacksonville, Florida.

Finally, many ZIP codes are for villages, census-designated places, portions of cities, or other entities that are not municipalities. For example, ZIP code 03750 is for Etna, New Hampshire, but Etna is not a city or town; it is actually a village district in the town of Hanover, which itself is assigned the ZIP code 03755. Another example is ZIP code 08043, which corresponds to the census-designated place of Kirkwood, NJ but actually serves the entirety of Voorhees Township, NJ. This is also the case in LaGrange, New York, a portion of which is served by the 12603 ZIP code based in the neighboring Town of Poughkeepsie. The rest of LaGrange is served by the LaGrangeville Post Office. LaGrangeville is itself, not a town at all, but a section of LaGrange. Another example is Armstrong Township of Vanderburgh County, Indiana. While the rest of the county uses the 477 prefix, Armstrong Township, despite having no incorporated town, uses the zip code 47617 and addresses itself "Armstrong, Indiana".

The postal designations for place names become de facto locations for their addresses, and as a result it is difficult to convince residents and businesses that they actually are located in another city or town different from the "default" place name associated with their ZIP codes. Because of the confusion and lack of identity generated by this situation, some cities, such as Signal Hill, California, have successfully petitioned the Postal Service to change ZIP-code boundaries or create new ZIP codes so that their cities can be the "default" place name for addresses within the ZIP code.

This confusion also can have financial implications for local governments, because mail volume is among the factors used by the U.S. Census Bureau to estimate population changes between decennial census enumerations. Sometimes local officials in a community that is not the "default" place name for a zip code but is an "acceptable" place name will advise residents to always use the name of the community, because if the census estimate of that town's population is low they will get fewer State and Federal funds that are computed based on population.