What is average mature area?

What is the average number of miles of a Zip code area in the United States? (e.g., how far in same zip)?

• I am trying to determine what is the average area square of a zip code in the united states. E.g., are most zip codes in cities/towns in the US 3 miles square? How are zip codes determined in the US?

• Answer:

  ZIP codes are not determined by geography. It is important to note that despite the geographic derivation of most ZIP codes, the codes themselves are not geographic regions, but simply categories for grouping mailing addresses. 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.