Rank U.S. counties by July 1, 2025 population. See exact Census estimates, the largest places, national shares, growth context and downloadable rankings.
Los Angeles County leads this resident population ranking with 9,694,934 residents. The reference population is July 1, 2025.
Los Angeles County, California leads this ranking with 9,694,934 residents on July 1, 2025. Cook County, Illinois follows with 5,194,625; the gap between them is 4,500,309 people. The ten largest counties together have 41,718,203 residents, equivalent to 12.21% of the national resident total.
That share is a descriptive comparison using matching dates and the same national universe. County equivalents form a non-overlapping national partition in this release. They can therefore be added when the source dates match.
Population size and growth tell different stories
The largest county in 2025 lost 301,576 residents between July 1, 2020 and July 1, 2025, a 3.02% decline. Its most recent one-year change was a loss of 53,934 residents. A high position in a population-size ranking does not imply a high position in a growth ranking.
For a comparison over time, use the six-year history on the place profile or the population comparison tool. A current ranking orders a single July 1 observation. It does not establish an all-time peak, a historical rank in an unsupported year or the size of a metropolitan area.
Comparison universe: 3,144 U.S. counties and county equivalents. Source: PEP Vintage 2025. Population date: July 1, 2025. Growth interval: July 1, 2024–2025. Ties share a competition rank; subsequent ranks skip tied positions. Filters produce a subset of this universe and do not change the national profile rank.
Why a large county is not the same as a large city
Los Angeles County, California contains 24.63% of its state's population. Its total describes the county boundary, including incorporated places and residents outside those places. The county name does not define a single city proper.
County equivalents include independent cities, parishes, boroughs and other units in the Census file. New York City's borough counties are separate records, while the city profile describes the whole incorporated city. Connecticut's current planning regions are also county equivalents in this release. Read each profile's geographic context before attaching an older county series.
Sources, calculation rules and downloadable results
Source: co-est2025-alldata.csv, Census Population Estimates Program, Vintage 2025, variables POPESTIMATE2024 and POPESTIMATE2025. Density additionally uses 2025 Gazetteer ALAND joined by official code. The retained source snapshot is pep-2025-r1; calculations use unrounded values.
Population order uses the exact July 1, 2025 count. Equal unrounded metric values share a competition rank, and the following rank skips the tied positions. Display rounding can make different underlying values look identical; the table order uses the originals.
Export visible rows after filtering to preserve the displayed subset. Use complete dataset downloads for all observations, or population research tools for a longer comparison. A ranking is a dated descriptive result, not an official forecast. Publication vintages can revise earlier years; retain the release identifier with your research.
