The most populated ZIP code in every state, led by Katy's 77494

The most populated ZIP code in the United States is 77494, the Katy ZIP code west of Houston in Fort Bend County, Texas. It had 140,157 residents in the U.S. Census Bureau's 2020-2024 American Community Survey. Lakewood, New Jersey's 08701 is right behind it at 139,149, just 1,008 fewer.

Eight states have a ZIP code with more than 100,000 people: Texas, New Jersey, Illinois, New York, California, Tennessee, Georgia, and Florida. At the other end, Vermont's biggest ZIP code is 05401 in Burlington, with 31,662 residents.

The Census Bureau does not count people by ZIP code exactly, because ZIP codes are mail routes, not areas. It publishes figures for ZIP Code Tabulation Areas, which are built from census blocks to match ZIP codes as closely as possible. The table below uses those areas, and the "mostly in" column names a city only when more than half of the ZIP code's land falls inside it, based on the bureau's 2020 ZIP-to-place relationship file.

Big ZIP codes tend to sit in two kinds of places. Some are dense city neighborhoods: 60629 on Chicago's Southwest Side, 11368 in Corona, Queens, 19124 in Philadelphia, and 20002 in Washington, D.C. All four are entirely or almost entirely inside one city.

Others sit on the suburban edges of big metros: Katy's 77494, 34787 near Winter Garden, Florida, 85142 in Pinal County outside Phoenix, and 30044 in Gwinnett County, Georgia. Most of their land lies outside any single city. Katy covers 18 percent of 77494, and the Horizon West area covers 37 percent of 34787, which is why the "mostly in" column is blank for them.

Size varies a lot by state. Texas has 1,989 ZIP code areas in the data and its biggest holds 140,157 people. Delaware has 68, and its biggest, 19720 in New Castle County, holds 62,392. Hawaii's largest, 96706 on Oahu's Ewa plain, has 83,692 residents, more than any ZIP code in Ohio, Pennsylvania, or Michigan.

For the ZIP codes with the most people nationwide, see our list of the largest ZIP codes in America. Most ZIP codes in the table link to their own page with income, age, housing, and other figures.

Sources

Population figures are from the U.S. Census Bureau's American Community Survey 5-year estimates for 2020-2024, table B01003, for ZIP Code Tabulation Areas. Each ZIP code is assigned to the state and county that contain most of it. City names come from the Census Bureau's 2020 ZCTA-to-place relationship file, by share of land area. Connecticut's figure was pulled directly from the Census Bureau's data API. Survey estimates for small areas carry margins of error, so ZIP codes with similar totals may not differ in fact.