List of ZIP Code prefixes

ZIP codes are numbered with the first number representing a certain group of U.S. states. The second and third numbers represent a region in that group of states or, in some cases, a large city. The fourth and fifth numbers 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. Other towns are often given ZIP codes in numerical order, usually numerically. Often, the biggest city in a prefix is given a zip code ending in 01.
This table lists the cities served by each three digit ZIP. If the city name is in CAPITALS, it a three-digit prefix just for that city. If the city is in "italics", it is given a zip code that ends in 01.
First digits.
The first digit of the ZIP code is used as follows: