The United States is one of the largest countries in the world by land area, spanning more than 3.5 million square miles. While Americans have many options when it comes to choosing a place to live, large shares of the population live in relatively small, densely-populated, urban areas.
Of the more than 3,000 counties and county equivalents nationwide, 25 are home to more than one in every five Americans.
Using data from the U.S. Census Bureau, 24/7 Wall St. identified the 25 most populous counties in America. Counties are ranked by their population as of July 1, 2021. Among the counties on this list, populations range from 1.5 million to nearly 10 million.
These counties span the country, though only two are in the Midwest. The largest share of counties on this list are in the West, including eight in California alone. Most of the counties on this list either contain or have some or all of the same borders as a major city. Here is a look at the largest cities in America.
Though each of these counties ranks among the largest in the U.S. by population, most have a smaller population now than they did one year ago. Housing prices in many of the most populous counties have soared in recent years. This has made them less affordable and led to rising outward migration. Falling birth rates and rising death rates during the pandemic have also contributed to population declines in these counties.
Over the past year, the number of people living in the metro areas on this list has fallen by over 600,000. In one county on this list, the population fell by nearly 7% in the last year. Here is a look at the American city most people are leaving.
Click here to see the 25 most populous counties in America
25. Suffolk County, New York
> Total population: 1,526,344
> 1-yr. population change: +0.1% (+2,245 people)
> Largest place in county: Brentwood
[in-text-ad]
24. Philadelphia County, Pennsylvania
> Total population: 1,576,251
> 1-yr. population change: -1.5% (-24,754 people)
> Largest place in county: Philadelphia
24/7 Wall St.
23. New York County, New York
> Total population: 1,576,876
> 1-yr. population change: -6.6% (-110,958 people)
> Largest place in county: Manhattan (NYC)
22. Sacramento County, California
> Total population: 1,588,921
> 1-yr. population change: +0.2% (+2,680 people)
> Largest place in county: Sacramento
[in-text-ad-2]
21. Middlesex County, Massachusetts
> Total population: 1,614,742
> 1-yr. population change: -0.9% (-14,680 people)
> Largest place in county: Lowell
20. Alameda County, California
> Total population: 1,648,556
> 1-yr. population change: -1.9% (-31,288 people)
> Largest place in county: Oakland
[in-text-ad]
19. Wayne County, Michigan
> Total population: 1,774,816
> 1-yr. population change: -0.9% (-15,409 people)
> Largest place in county: Detroit
24/7 Wall St.
18. Santa Clara County, California
> Total population: 1,885,508
> 1-yr. population change: -2.3% (-45,090 people)
> Largest place in county: San Jose
17. Broward County, Florida
> Total population: 1,930,983
> 1-yr. population change: -0.5% (-10,533 people)
> Largest place in county: Fort Lauderdale
[in-text-ad-2]
16. Bexar County, Texas
> Total population: 2,028,236
> 1-yr. population change: +0.7% (+14,184 people)
> Largest place in county: San Antonio
15. Tarrant County, Texas
> Total population: 2,126,477
> 1-yr. population change: +0.6% (+11,768 people)
> Largest place in county: Fort Worth
[in-text-ad]
14. San Bernardino County, California
> Total population: 2,194,710
> 1-yr. population change: +0.5% (+11,970 people)
> Largest place in county: San Bernardino
24/7 Wall St.
13. King County, Washington
> Total population: 2,252,305
> 1-yr. population change: -0.9% (-20,266 people)
> Largest place in county: Seattle
12. Clark County, Nevada
> Total population: 2,292,476
> 1-yr. population change: +0.8% (+19,090 people)
> Largest place in county: Las Vegas
[in-text-ad-2]
11. Queens County, New York
> Total population: 2,331,143
> 1-yr. population change: -2.7% (-64,648 people)
> Largest place in county: Queens (NYC)
10. Riverside County, California
> Total population: 2,458,395
> 1-yr. population change: +1.5% (+35,631 people)
> Largest place in county: Riverside
[in-text-ad]
9. Dallas County, Texas
> Total population: 2,586,050
> 1-yr. population change: -1.0% (-24,907 people)
> Largest place in county: Dallas
24/7 Wall St.
8. Kings County, New York
> Total population: 2,641,052
> 1-yr. population change: -3.2% (-86,341 people)
> Largest place in county: Brooklyn (NYC)
7. Miami-Dade County, Florida
> Total population: 2,662,777
> 1-yr. population change: -1.1% (-29,682 people)
> Largest place in county: Miami
[in-text-ad-2]
6. Orange County, California
> Total population: 3,167,809
> 1-yr. population change: -0.5% (-16,292 people)
> Largest place in county: Anaheim
5. San Diego County, California
> Total population: 3,286,069
> 1-yr. population change: -0.3% (-11,183 people)
> Largest place in county: San Diego
[in-text-ad]
4. Maricopa County, Arizona
> Total population: 4,496,588
> 1-yr. population change: +1.3% (+58,246 people)
> Largest place in county: Phoenix
3. Harris County, Texas
> Total population: 4,728,030
> 1-yr. population change: -0.1% (-4,461 people)
> Largest place in county: Houston
2. Cook County, Illinois
> Total population: 5,173,146
> 1-yr. population change: -1.7% (-89,595 people)
> Largest place in county: Chicago
[in-text-ad-2]
1. Los Angeles County, California
> Total population: 9,829,544
> 1-yr. population change: -1.6% (-159,621 people)
> Largest place in county: Los Angeles
Find a Qualified Financial Advisor (Sponsor)
Finding a qualified financial advisor doesn’t have to be hard. SmartAsset’s free tool matches you with up to 3 fiduciary financial advisors in your area in 5 minutes. Each advisor has been vetted by SmartAsset and is held to a fiduciary standard to act in your best interests. If you’re ready to be matched with local advisors that can help you achieve your financial goals, get started now.
Thank you for reading! Have some feedback for us?
Contact the 24/7 Wall St. editorial team.
Latest from 24/7
