US County Populations 2020

According to the most recent United States Census, Los Angeles County in California is the largest county in the nation, with a total population of 10,150,558 – an increase of 3.5% since 2010. Chicago's Cook County follows and, although very large in its own right, is half the size of Los Angeles County with 5,231,356 residents. Harris County in Texas, Maricopa County in Arizona, and San Diego County in California make up the rest of the top five – all have populations in excess of three million.

Counties with Positive Population Growth

Statistics from 2018 show that a number of counties have had substantial population growths since 2010. Fort Bend County in Texas tops the list, with its population having grown from 590,286 in 2010 to well over a population of 764,000 in 2018 – an increase of 30.8%. Three other counties in Texas are also in the top five counties with increased populations. These are Denton County (with an increase of 26.2%), Collin County (24%) and Travis County (19.7%).

Counties with Negative Population Growth

Conversely, while Wayne County is the most populous county in state of Michigan, it has seen its population decrease by 3.7% since 2010, from 1,815,069 to 1,756,598. Counties in two other midwestern states, Missouri and Ohio, have also had population decreases, although both are more modest. Ohio's Cuyahoga County has decreased from 1,278,200 to just around 1,248,000, representing a reduction of 2.5%, while St. Louis County, Missouri's population has decreased from 998,681 in 2010 to 998,216 in 2018. Just one county, Hartford County in Connecticut, shows nearly zero population change, with census figures reporting a population of approximately 895,500 in both 2010 and 2018.

County Name State 2020 Population 2010 Population Growth (since 2010)
Los Angeles CountyCalifornia10,105,5009,822,4302.88%
Cook CountyIllinois5,180,4905,199,170-0.36%
Harris CountyTexas4,698,6204,107,83014.38%
Maricopa CountyArizona4,410,8203,825,19015.31%
San Diego CountyCalifornia3,343,3603,103,3107.74%
Orange CountyCalifornia3,185,9703,016,5605.62%
Miami-Dade CountyFlorida2,761,5802,507,06010.15%
Dallas CountyTexas2,637,7702,372,33011.19%
Kings CountyNew York2,582,8302,509,8802.91%
Riverside CountyCalifornia2,450,7602,201,65011.31%
Queens CountyNew York2,278,9102,234,7401.98%
King CountyWashington2,233,1601,938,38015.21%
Clark CountyNevada2,231,6501,952,64014.29%
San Bernardino CountyCalifornia2,171,6002,040,9106.40%
Tarrant CountyTexas2,084,9301,817,51014.71%
Bexar CountyTexas1,986,0501,722,86015.28%
Broward CountyFlorida1,951,2601,752,83011.32%
Santa Clara CountyCalifornia1,937,5701,786,0808.48%
Wayne CountyMichigan1,753,8901,815,160-3.38%
Alameda CountyCalifornia1,666,7501,513,04010.16%
New York CountyNew York1,628,7001,588,7602.51%
Middlesex CountyMassachusetts1,614,7101,507,6907.10%
Philadelphia CountyPennsylvania1,584,1401,528,2903.65%
Sacramento CountyCalifornia1,540,9801,421,4108.41%
Palm Beach CountyFlorida1,485,9401,323,65012.26%
Suffolk CountyNew York1,481,0901,494,380-0.89%
Hillsborough CountyFlorida1,436,8901,233,49016.49%
Bronx CountyNew York1,432,1301,387,3503.23%
Orange CountyFlorida1,380,6401,148,59020.20%
Nassau CountyNew York1,358,3401,341,6901.24%
Franklin CountyOhio1,310,3001,166,26012.35%
Hennepin CountyMinnesota1,259,4301,154,1909.12%
Oakland CountyMichigan1,259,2001,203,1204.66%
Travis CountyTexas1,248,7401,030,54021.17%
Cuyahoga CountyOhio1,243,8601,278,100-2.68%
Allegheny CountyPennsylvania1,218,4501,223,970-0.45%
Salt Lake CountyUtah1,152,6301,032,98011.58%
Fairfax CountyVirginia1,150,8001,086,1305.95%
Contra Costa CountyCalifornia1,150,2201,052,5609.28%
Mecklenburg CountyNorth Carolina1,093,900923,25818.48%
Wake CountyNorth Carolina1,092,300906,88220.45%
Montgomery CountyMaryland1,052,570976,2877.81%
Fulton CountyGeorgia1,050,110925,65113.45%
Pima CountyArizona1,039,070981,6535.85%
Collin CountyTexas1,005,150788,43127.49%
St. Louis CountyMissouri996,945998,843-0.19%
Fresno CountyCalifornia994,400932,0636.69%
Honolulu CountyHawaii980,080956,2962.49%
Pinellas CountyFlorida975,280916,4246.42%
Westchester CountyNew York967,612950,6311.79%
Marion CountyIndiana954,670904,6025.53%
Duval CountyFlorida950,181865,6379.77%
Milwaukee CountyWisconsin948,201948,301-0.01%
Fairfield CountyConnecticut943,823919,3302.66%
Bergen CountyNew Jersey936,692906,3413.35%
Shelby CountyTennessee935,764928,4480.79%
DuPage CountyIllinois928,589918,0291.15%
Gwinnett CountyGeorgia927,781808,04914.82%
Erie CountyNew York919,719919,1430.06%
Prince George's CountyMaryland909,308865,7475.03%
Kern CountyCalifornia896,764841,0726.62%
Hartford CountyConnecticut892,697895,226-0.28%
Pierce CountyWashington891,299795,39312.06%
San Francisco CountyCalifornia883,305805,5509.65%
Macomb CountyMichigan874,759841,3553.97%
Hidalgo CountyTexas865,939779,21311.13%
Denton CountyTexas859,064666,76828.84%
New Haven CountyConnecticut857,620863,382-0.67%
Ventura CountyCalifornia850,967825,1303.13%
El Paso CountyTexas840,758803,6554.62%
Worcester CountyMassachusetts830,839800,4013.80%
Middlesex CountyNew Jersey829,685810,6662.35%
Montgomery CountyPennsylvania828,604800,9073.46%
Baltimore CountyMaryland828,431806,5602.71%
Hamilton CountyOhio816,684802,2631.80%
Snohomish CountyWashington814,901715,50713.89%
Multnomah CountyOregon811,880737,29110.12%
Suffolk CountyMassachusetts807,252725,81911.22%
Essex CountyNew Jersey799,767784,0622.00%
Oklahoma CountyOklahoma792,582720,7879.96%
Essex CountyMassachusetts790,638745,4796.06%
Fort Bend CountyTexas787,858590,26033.48%
Jefferson CountyKentucky770,517742,0503.84%
San Mateo CountyCalifornia769,545719,7256.92%
Cobb CountyGeorgia756,865689,5289.77%
DeKalb CountyGeorgia756,558692,4719.25%
Lee CountyFlorida754,610620,45421.62%
San Joaquin CountyCalifornia752,660687,1569.53%
Monroe CountyNew York742,474744,594-0.28%
Denver CountyColorado716,492603,35418.75%
El Paso CountyColorado713,856626,90413.87%
Polk CountyFlorida708,009603,12817.39%
Norfolk CountyMassachusetts705,388673,0394.81%
District of ColumbiaDistrict of Columbia702,455605,08516.09%
Lake CountyIllinois700,832704,192-0.48%
Jackson CountyMissouri700,307674,8243.78%
Davidson CountyTennessee692,587627,75310.33%
Will CountyIllinois692,310678,8181.99%
Bernalillo CountyNew Mexico678,701663,9482.22%
Hudson CountyNew Jersey676,061635,6346.36%