Zip Codes

Six months after the implementation of ZIP codes in 1963, every address in the US had been assigned one.

Zip codes, also known as postal codes, are a system of numerical codes that are used by postal services to facilitate the delivery of mail and parcels to specific locations. The history of zip codes goes back to the early 20th century when the United States Postal Service (USPS) recognized the need for a more efficient mail delivery system.

In 1943, the USPS introduced a system of postal zones that were used to expedite the delivery of mail within large cities. The system was based on a series of one or two-digit numbers that were added to the end of the city name on the address line. While this system was an improvement, it still had limitations, particularly in rural areas.

In the 1960s, the USPS embarked on a major project to develop a more comprehensive and standardized system of postal codes. The result was the introduction of the ZIP (Zone Improvement Plan) code system in 1963. The ZIP code system was based on a five-digit code that could be used to identify a specific location anywhere in the United States.

The first digit – is the region of the country
  • 0 = Connecticut (CT), Massachusetts (MA), Maine (ME), New Hampshire (NH), New Jersey (NJ), New York (NY, Fishers Island only), Puerto Rico (PR), Rhode Island (RI), Vermont (VT), Virgin Islands (VI), Army Post Office Europe, Central Asia, and the Middle East (APO AE); Fleet Post Office Europe and the Middle East (FPO 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), Army Post Office Americas (APO AA), Fleet Post Office Americas (FPO 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), Army Post Office Pacific (APO AP), Fleet Post Office Pacific (FPO AP)
The second and third digits – represent a sectional center facility (SCF) within that region (examples below)
  • San Juan, Puerto Rico (006-007, 009)
  • United States Virgin Islands (008)
  • Boston, Massachusetts (021-022, 024)
  • Eastern Maine (044, 046, 047, 049)
  • Pittsburgh, Pennsylvania (150-154, 156, 160-165
  • Wilmington, Delaware (197-199)
  • Washington D.C. US government, agencies, etc. (202-205)
  • Baltimore, Maryland (212, 215, 217, 219)
  • Birmingham, Alabama (350-352, 354-359, 362)
  • Atlanta, Georgia (301-303, 311, IRS 399)
  • Nashville, Tennessee (370-372, 384, 385)
  • Indianapolis, Indiana (460-462, 469, 472, 474, 478-479)
  • Lexington, Kentucky (403-406, 413-414)
  • Minneapolis, Minnesota (553-555)
  • Sioux Falls, South Dakota (570-571)
  • Omaha, Nebraska (680-681, 683-689)
  • Little Rock, Arkansas (716-717, 719-722, 725, 728)
  • Dallas, Texas (751-753)
  • Cheyenne, Wyoming (820, 822-823)
  • Las Vegas, Nevada (889-891, 893)
  • Reno, Nevado (894-895, 897)
  • Los Angeles, California (900-905, 907, 908)
  • San Diego, California (919-921)
  • Honolulu, Hawaii (967-968)
  • Anchorage, Alaska (995-997)
The last two digits – represented a specific post office or delivery area within the SCF.
  • For example, in a 10014 ZIP code, the first “1” stands for Delaware, New York, Pennsylvania; the “00” stands for New York Sectional Center Facility; and “14” stands for the part of Manhattan (Meatpacking and the West Village).

Robert Moon is considered the father of the ZIP Code; he submitted his proposal in 1944 while working as a postal inspector. The phrase “zone improvement plan” is credited to D. Jamison Cain, a Postal Service executive.

The post office credits Moon with only the first three digits of the ZIP Code, which describe the sectional center facility (SCF)[1] or “sec center”. An SCF is a central mail processing facility with those three digits. The fourth and fifth digits, which give a more precise locale within the SCF, were proposed by Henry Bentley Hahn, Sr.

In addition to standard five-digit zip codes, in 1983, the USPS introduced ZIP+4 codes, which consist of the standard five-digit code followed by four additional digits that further refine the location of a specific address.

These additional digits can help to speed up mail delivery by providing more detailed information about a particular address. city block, a group of apartments, an individual high-volume receiver of mail, a post office box, or any other unit that could use an extra identifier to aid in efficient mail sorting and delivery. However, the new format was not adopted universally by the public; it eventually became obsolete with modern technology.

Mr. Zip was a cartoon character created by the United States Postal Service (USPS) in 1963 to help promote the use of ZIP codes. The character was designed to make the concept of zip codes more accessible and easy to understand for the general public. Mr. Zip was depicted as a friendly and approachable character, with a red, white, and blue striped outfit and a large “Z” on his chest.

He was often shown carrying a large envelope or package and was used in a variety of promotional materials, including posters, ads, and educational materials. The character’s slogan, “Use Zip Code”, was widely recognized and helped to increase public awareness and understanding of the new ZIP code system. Today, Mr. Zip is still occasionally used in USPS promotional materials and is recognized as an important part of the history of the postal service.

While the term “postal code” is often used interchangeably with “zip code” in the United States, postal codes can refer to a variety of different systems used in different countries. For example, Canada uses a six-character alphanumeric postal code system, while the United Kingdom uses a system of alphanumeric codes with variable lengths.

Zip codes play a critical role in mail delivery within the United States, as they help to ensure that mail is delivered to the correct recipient promptly. They also facilitate the sorting and processing of mail within postal systems, allowing for more efficient and accurate delivery.

In popular culture, there is 90210: Beverly Hills, California.
We all know this ZIP code. The hit teen TV drama, 90210, was modeled after the glam shenanigans that occurred in this area’s manicured streets. It is also home to the Greystone Mansion, where over 50 movies were filmed.

  1. A Sectional Center Facility (SCF) is a central mail processing facility in the United States Postal Service (USPS) that serves as a hub for the processing and distribution of mail within a specific geographic region. SCFs are responsible for sorting and processing mail from smaller post offices and delivering it to the appropriate destination. Each SCF serves a specific area, which can range from a single zip code to multiple zip codes within a larger geographic region. SCFs are typically located in major cities or metropolitan areas and are responsible for processing large volumes of mail daily. In addition to sorting and processing mail, SCFs also play a role in the distribution of mail to local post offices within their designated service area. Mail is transported from the SCF to local post offices for final delivery to the recipient. [Back]

Further Reading


Universal Postal Union
Readers Digest
Smithsonian National Postal Museum

Author: Doyle

I was born in Atlanta, moved to Alpharetta at 4, lived there for 53 years and moved to Decatur in 2016. I've worked at such places as Richway, North Fulton Medical Center, Management Science America (Computer Tech/Project Manager) and Stacy's Compounding Pharmacy (Pharmacy Tech).

Leave a Reply

%d bloggers like this: