Meaning of US ZIP code digits

ZIP code is a number consisted of five digits from 0 to 9. The USA is divided into geographical areas and the first digit of zip code represents one of these areas. There is a list of areas:

• 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

The next two digits of zip code represent a region in that geographical area. In other words, the first three digits stand for the sectional center facility. The fourth and fifth zip code digits indicate the area of the city or a village/town.