County facts · United States · October 22, 2026
Most Populous Counties in the US (2023 Estimates)
The 25 most populous US counties in the Census Bureau's 2023 estimates, with land area, people per square mile and each official parcel map.
Looking for the most populous counties in the US? The largest by people is Los Angeles County, CA, with about 9,663,345 residents in the Census Bureau's July 1, 2023 estimate, more than 40 of the 50 states. Next come Cook County, IL (5,087,072) and Harris County, TX (4,835,125).
48 counties had at least one million residents in the 2023 estimates. The 25 below hold about 21% of everyone in the country.
The 25 most populous US counties
| # | County | State | 2023 pop. | Land (sq mi) | People per sq mi | Parcel viewer |
|---|---|---|---|---|---|---|
| 1 | Los Angeles County | California | 9,663,345 | 4,059 | 2,381 | county web map |
| 2 | Cook County | Illinois | 5,087,072 | 945 | 5,384 | county web map |
| 3 | Harris County | Texas | 4,835,125 | 1,707 | 2,833 | appraisal district map |
| 4 | Maricopa County | Arizona | 4,585,871 | 9,202 | 498 | county web map |
| 5 | San Diego County | California | 3,269,973 | 4,210 | 777 | ArcGIS Map Viewer |
| 6 | Orange County | California | 3,135,755 | 793 | 3,955 | county web map |
| 7 | Miami-Dade County | Florida | 2,686,867 | 1,900 | 1,414 | county web map |
| 8 | Dallas County | Texas | 2,606,358 | 873 | 2,985 | appraisal district map |
| 9 | Kings County | New York | 2,561,225 | 69 | 36,917 | county web map |
| 10 | Riverside County | California | 2,492,442 | 7,209 | 346 | county web map |
| 11 | Clark County | Nevada | 2,336,573 | 7,892 | 296 | County Parcels in Nevada layer in ArcGIS Map Viewer |
| 12 | King County | Washington | 2,271,380 | 2,115 | 1,074 | county web map |
| 13 | Queens County | New York | 2,252,196 | 109 | 20,715 | county web map |
| 14 | San Bernardino County | California | 2,195,611 | 20,068 | 109 | county web map |
| 15 | Tarrant County | Texas | 2,182,947 | 865 | 2,523 | county web map |
| 16 | Bexar County | Texas | 2,087,679 | 1,240 | 1,683 | county web map |
| 17 | Broward County | Florida | 1,962,531 | 1,203 | 1,632 | county web map |
| 18 | Santa Clara County | California | 1,877,592 | 1,291 | 1,454 | county web map |
| 19 | Wayne County | Michigan | 1,751,169 | 612 | 2,862 | ArcGIS Experience Builder |
| 20 | Middlesex County | Massachusetts | 1,623,952 | 818 | 1,986 | MassGIS Interactive Property Map |
| 21 | Alameda County | California | 1,622,188 | 737 | 2,200 | ArcGIS Web AppBuilder |
| 22 | New York County | New York | 1,597,451 | 23 | 70,509 | county web map |
| 23 | Sacramento County | California | 1,584,288 | 965 | 1,641 | county web map |
| 24 | Philadelphia County | Pennsylvania | 1,550,542 | 134 | 11,541 | county web map |
| 25 | Hillsborough County | Florida | 1,535,564 | 1,022 | 1,503 | county web map |
New York City's five boroughs are each their own county, which is why Kings (Brooklyn) and Queens rank here while "New York City" as a whole does not appear.
Which states hold the most populous counties
- California: 8 of the top 25
- Texas: 4 of the top 25
- Florida: 3 of the top 25
- New York: 3 of the top 25
- One each: Arizona, Illinois, Massachusetts, Michigan, Nevada, Pennsylvania and Washington.
Population versus land
Size and population rarely go together. Los Angeles County, CA covers about 4,059 square miles, while New York County, NY packs about 70,509 people into each square mile. If you are searching parcels in one of these counties, expect small city lots, condominium units listed as separate parcels, and parcel numbers that change when lots are split or combined.
Connecticut is the one awkward fit. The 2020 Gazetteer still has its 8 historic counties, but since 2022 the Census Bureau has used Connecticut's 9 planning regions as its county equivalents, so the 2023 estimates are by planning region. None of its planning regions reaches the top 25.
Related guides
- Largest counties in the US by land area
- Largest county in each state
- Smallest county in each state
- Smallest counties in the US
- Least populated counties in the US
- Most densely populated counties in the US
- How many counties are in the US
Sources
- U.S. Census Bureau Gazetteer files, 2020 county land and water area (50 states and the District of Columbia; Puerto Rico's municipios are left out).
- U.S. Census Bureau, Population Estimates Program, county totals, Vintage 2023 (July 1, 2023 estimates)
- Platbookmapper county GIS directory (live data file behind our county pages, pulled October 22, 2026) for each official parcel viewer.