_San Diego, California Postal Code

San Diego, California Zip Code is : 92101

ZIP Codes are 5-digit numbers developed by the United States Postal Service (USPS) to represent individual post offices across the United States. A ZIP Code is just the name of the postal code system for the United States.

There are three main parts of the 5-digit ZIP Code - the national area, the region or city, and the delivery area. The United States Postal Service has segmented the country into 10 ZIP Code areas. Starting in the northeast, they are numbered 0-9.

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

ZIP Codes Beginning With	States
0	Connecticut, Massachusetts, Maine, New Hampshire, New Jersey, Puerto Rico, Rhode Island, Vermont, Virgin Islands, Army Post Office Europe, Fleet Post Office Europe
1	Delaware, New York, Pennsylvania
2	District of Columbia, Maryland, North Carolina, South Carolina, Virginia, West Virginia
3	Alabama, Florida, Georgia, Mississippi, Tennessee, Army Post Office Americas, Fleet Post Office Americas
4	Indiana, Kentucky, Michigan, Ohio
5	Iowa, Minnesota, Montana, North Dakota, South Dakota, Wisconsin
6	Illinois, Kansas, Missouri, Nebraska
7	Arkansas, Louisiana, Oklahoma, Texas
8	Arizona, Colorado, Idaho, New Mexico, Nevada, Utah, Wyoming
9	Alaska, American Samoa, California, Guam, Hawaii, Marshall Islands, Federated States of Micronesia, Northern Mariana Islands, Oregon, Palau, Washington, Army Post Office Pacific, Fleet Post Office Pacific

After the first number in a ZIP Code is assigned, the USPS assigns the next two numbers according to a city. If a region has a main town or city, the USPS will often assign it the first ZIP Codes. After that, the ZIP Codes will proceed alphabetically.

The first three digits of a ZIP Code together usually indicate the sectional center facility to which that ZIP Code belongs. This facility is the mail sorting and distribution center for a zone or area. Some sectional center facilities have multiple three-digit codes assigned to them.

The fourth and fifth digits of the ZIP Code represent the area of the city or town.

ZIP code data is an integral part of business operations in the United States. It's an important parameter for sending mail, managing fraud detection, or researching demographic information.

The ZIP+4 code is used and assigned by the United States Postal Service (USPS) for routing purposes. A ZIP+4 code uses the basic five-digit code plus four additional digits to identify a geographic segment within the five-digit delivery area, such as a city block, a group of apartments, an individual high-volume receiver of mail.