United States Zip Code Overview

ZIP codes are a system of postal codes used by the United States Postal Service ( USPS) since 1963. Before 1963, cities simply had postal zones” in 124 of the nation's most populated areas But when mail started to boom, in order to meet the growing demand, the U.S. Postal Service decided to add five numbers to addresses to make mail more efficient as a part of a Zone Improvement Plan (the ZIP in ZIP code stands for Zone Improvement Plan). ZIP codes are used by the US Postal Service to map the most efficient routes for mail carriers to follow.

ZIP Codes are numbered with the first digit representing a certain group of U.S. states, the second and third digits together representing a region in that group (or perhaps a large city) and the fourth and fifth digits representing a group of delivery addresses within that region. The fourth and fifth digits were proposed by Henry Bentley Hahn Sir which gives a more precise locale within the SCF 6 The SCF sorts mail to all post offices with those first three digits in their ZIP Codes. Robert Moon is considered the father of the ZIP Code. He submitted his proposal in 1944 while working as a postal inspector 5 The post office only credits Moon with the first three digits of the ZIP Code, which describe the sectional center facility (SCF) or "sec center." An SCF is a central mail processing facility with those three digits.

Reference : WikiPedia

Top States by Population in United States

State Zip Codes Cities Population Timezones
California 2,587 1,237 37,253,956 Pacific (GMT -08:00)
Texas 2,594 1,467 25,145,561 Central (GMT -06:00) Mountain (GMT -07:00)
New york 2,149 1,608 19,378,102 Eastern (GMT -05:00)
Florida 1,470 527 18,801,310 Eastern (GMT -05:00) Central (GMT -06:00)
Illinois 1,568 1,278 12,830,632 Central (GMT -06:00)
Pennsylvania 2,173 1,785 12,702,379 Eastern (GMT -05:00)
Ohio 1,415 1,063 11,536,504 Eastern (GMT -05:00)
Michigan 1,158 879 9,883,640 Central (GMT -06:00) Eastern (GMT -05:00)
Georgia 951 629 9,687,653 Eastern (GMT -05:00)
North carolina 1,079 757 9,535,483 Eastern (GMT -05:00)

Top Cities by Population in United States

City State Zip Codes Population Timezones
New york New York 145 8,175,133 Eastern (GMT -05:00)
Los angeles California 97 3,792,621 Pacific (GMT -08:00)
Chicago Illinois 90 2,695,598 Central (GMT -06:00)
Houston Texas 178 2,099,451 Central (GMT -06:00)
Philadelphia Pennsylvania 87 1,526,006 Eastern (GMT -05:00)
Phoenix Arizona 75 1,445,632 Mountain (GMT -07:00)
San antonio Texas 85 1,327,407 Central (GMT -06:00)
San diego California 80 1,307,402 Pacific (GMT -08:00)
Dallas Texas 105 1,197,816 Central (GMT -06:00)
San jose California 59 945,942 Pacific (GMT -08:00)

Top Zip Code by Population in United States

Zip Code City State AreaCode Population Timezone
Zip Code 77449 Katy Texas 832 / 346 / 281 124,161 Central (GMT -06:00)
Zip Code 77494 Katy Texas 281 / 346 / 832 121,708 Central (GMT -06:00)
Zip Code 79936 El Paso Texas 915 118,608 Mountain (GMT -07:00)
Zip Code 77084 Houston Texas 281 / 832 / 346 109,885 Central (GMT -06:00)
Zip Code 90011 Los Angeles California 323 109,773 Pacific (GMT -08:00)
Zip Code 60629 Chicago Illinois 773 / 872 / 312 / 708 108,911 Central (GMT -06:00)
Zip Code 90650 Norwalk California 562 104,861 Pacific (GMT -08:00)
Zip Code 08701 Lakewood New Jersey 732 / 848 104,346 Eastern (GMT -05:00)
Zip Code 78521 Brownsville Texas 956 103,832 Central (GMT -06:00)
Zip Code 78572 Mission Texas 956 103,451 Central (GMT -06:00)
Zip Code 90201 Bell Gardens California 323 102,119 Pacific (GMT -08:00)
Zip Code 92335 Fontana California 909 102,029 Pacific (GMT -08:00)
Zip Code 92336 Fontana California 909 101,643 Pacific (GMT -08:00)
Zip Code 78660 Pflugerville Texas 512 101,532 Central (GMT -06:00)
Zip Code 90250 Hawthorne California 310 / 424 100,092 Pacific (GMT -08:00)
Zip Code 94565 Pittsburg California 925 98,901 Pacific (GMT -08:00)
Zip Code 77433 Cypress Texas 832 / 281 / 346 98,872 Central (GMT -06:00)
Zip Code 11226 Brooklyn New York 718 97,341 Eastern (GMT -05:00)
Zip Code 90280 South Gate California 323 97,204 Pacific (GMT -08:00)
Zip Code 90805 Long Beach California 562 / 310 96,340 Pacific (GMT -08:00)