US County Populations 2021

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 2021 Population 2010 Population Growth (since 2010)
Los Angeles CountyCalifornia9,969,5109,823,2501.49%
Cook CountyIllinois5,106,7805,199,020-1.77%
Harris CountyTexas4,779,8804,107,67016.36%
Maricopa CountyArizona4,651,4403,825,11021.60%
San Diego CountyCalifornia3,347,2703,103,2107.86%
Orange CountyCalifornia3,175,1303,015,1705.31%
Miami-Dade CountyFlorida2,721,1102,506,9708.54%
Dallas CountyTexas2,647,8502,372,99011.58%
Kings CountyNew York2,523,5602,509,8300.55%
Riverside CountyCalifornia2,520,0602,201,58014.47%
Clark CountyNevada2,347,9201,952,59020.25%
King CountyWashington2,301,6201,938,35018.74%
Queens CountyNew York2,212,3602,234,700-1.00%
San Bernardino CountyCalifornia2,206,7502,040,8508.13%
Tarrant CountyTexas2,144,6501,817,48018.00%
Bexar CountyTexas2,048,2901,722,84018.89%
Broward CountyFlorida1,966,1201,752,80012.17%
Santa Clara CountyCalifornia1,918,8801,786,0407.44%
Wayne CountyMichigan1,739,1201,815,080-4.18%
Alameda CountyCalifornia1,680,4801,512,99011.07%
New York CountyNew York1,628,0101,588,7702.47%
Middlesex CountyMassachusetts1,618,1601,507,6807.33%
Philadelphia CountyPennsylvania1,585,0101,528,2803.71%
Sacramento CountyCalifornia1,578,6801,421,38011.07%
Palm Beach CountyFlorida1,524,5601,323,62015.18%
Hillsborough CountyFlorida1,512,0701,233,50022.58%
Suffolk CountyNew York1,468,1401,494,340-1.75%
Orange CountyFlorida1,417,2801,148,56023.40%
Bronx CountyNew York1,390,4501,387,3000.23%
Nassau CountyNew York1,355,7001,341,6701.05%
Franklin CountyOhio1,334,8701,166,20014.46%
Travis CountyTexas1,328,7201,030,50028.94%
Hennepin CountyMinnesota1,281,6801,154,19011.05%
Oakland CountyMichigan1,259,3601,203,1104.68%
Cuyahoga CountyOhio1,221,7801,278,090-4.41%
Allegheny CountyPennsylvania1,213,5701,223,960-0.85%
Salt Lake CountyUtah1,183,9301,032,98014.61%
Contra Costa CountyCalifornia1,159,5401,052,54010.17%
Wake CountyNorth Carolina1,152,740906,87027.11%
Fairfax CountyVirginia1,145,6701,086,1605.48%
Mecklenburg CountyNorth Carolina1,143,570923,24223.86%
Collin CountyTexas1,095,580787,61439.10%
Fulton CountyGeorgia1,091,550925,63217.92%
Pima CountyArizona1,068,730981,6208.87%
Montgomery CountyMaryland1,055,110975,6028.15%
Fresno CountyCalifornia1,013,400932,0398.73%
St. Louis CountyMissouri992,177998,840-0.67%
Pinellas CountyFlorida978,872916,4126.82%
Marion CountyIndiana976,346904,5917.93%
Duval CountyFlorida975,961865,62812.75%
Westchester CountyNew York966,092950,6011.63%
Honolulu CountyHawaii963,973956,2850.80%
Gwinnett CountyGeorgia954,076808,00718.08%
Denton CountyTexas944,139666,76041.60%
Milwaukee CountyWisconsin943,240948,285-0.53%
Fairfield CountyConnecticut942,054919,3552.47%
Shelby CountyTennessee938,768928,4471.11%
Bergen CountyNew Jersey930,974906,2842.72%
Pierce CountyWashington927,428795,39016.60%
Erie CountyNew York916,672919,152-0.27%
DuPage CountyIllinois914,269917,983-0.40%
Kern CountyCalifornia913,090840,9968.57%
Prince George's CountyMaryland908,743866,4194.88%
Hartford CountyConnecticut890,000895,236-0.58%
San Francisco CountyCalifornia883,255805,5059.65%
Hidalgo CountyTexas881,525779,14913.14%
Macomb CountyMichigan876,326841,3524.16%
Fort Bend CountyTexas858,902590,25345.51%
New Haven CountyConnecticut850,329863,357-1.51%
El Paso CountyTexas844,064803,5765.04%
Ventura CountyCalifornia841,734825,0972.02%
Snohomish CountyWashington840,131715,50017.42%
Montgomery CountyPennsylvania838,897800,8744.75%
Worcester CountyMassachusetts833,758800,3914.17%
Baltimore CountyMaryland826,392806,6562.45%
Middlesex CountyNew Jersey822,842810,7581.49%
Hamilton CountyOhio821,529802,2782.40%
Multnomah CountyOregon820,421737,27611.28%
Oklahoma CountyOklahoma811,116720,76212.54%
Suffolk CountyMassachusetts805,427725,77210.98%
Lee CountyFlorida802,791620,44929.39%
Essex CountyNew Jersey799,785784,0372.01%
Essex CountyMassachusetts790,736745,4616.07%
San Joaquin CountyCalifornia781,462687,12713.73%
Cobb CountyGeorgia768,283689,49511.43%
DeKalb CountyGeorgia768,079692,44310.92%
Jefferson CountyKentucky764,069742,0542.97%
San Mateo CountyCalifornia762,357719,6995.93%
Polk CountyFlorida761,137603,10226.20%
Denver CountyColorado749,103603,35924.16%
Monroe CountyNew York739,582744,580-0.67%
El Paso CountyColorado737,031627,03117.54%
District of ColumbiaDistrict of Columbia714,153605,22618.00%
Norfolk CountyMassachusetts713,865673,0196.07%
Jackson CountyMissouri707,465674,8454.83%
Davidson CountyTennessee701,400627,74611.73%
Lake CountyIllinois690,431704,170-1.95%
Will CountyIllinois689,931678,8241.64%
Bernalillo CountyNew Mexico681,295663,9232.62%
Hudson CountyNew Jersey673,311635,6525.92%
Arapahoe CountyColorado666,176574,74715.91%
Utah CountyUtah665,665519,99828.01%
Kent CountyMichigan664,165602,97510.15%
Tulsa CountyOklahoma659,290604,9738.98%
Jefferson CountyAlabama656,861658,215-0.21%
Providence CountyRhode Island642,887627,8382.40%
Montgomery CountyTexas642,633459,20839.94%
Williamson CountyTexas638,727426,28749.83%
Bucks CountyPennsylvania629,186625,3850.61%
Ocean CountyNew Jersey618,602577,5647.11%
Monmouth CountyNew Jersey615,467630,461-2.38%
Brevard CountyFlorida615,420543,96513.14%
Washington CountyOregon610,968531,63814.92%
Johnson CountyKansas610,949545,65511.97%
Jefferson CountyColorado589,859535,54810.14%
Anne Arundel CountyMaryland586,656539,2848.78%
Pasco CountyFlorida583,661465,48725.39%
Douglas CountyNebraska581,199518,57412.08%
Baltimore cityMaryland575,584620,915-7.30%
Delaware CountyPennsylvania569,779558,9811.93%
Volusia CountyFlorida567,650494,44014.81%
Bristol CountyMassachusetts567,467549,1663.33%
New Castle CountyDelaware561,159538,7524.16%
Union CountyNew Jersey556,219537,3693.51%
Dane CountyWisconsin556,189489,21813.69%
Stanislaus CountyCalifornia555,728515,1457.88%
Ramsey CountyMinnesota553,219509,3878.60%
Lancaster CountyPennsylvania549,234520,3195.56%
Guilford CountyNorth Carolina546,308489,61811.58%
Greenville CountySouth Carolina541,384452,69719.59%
Spokane CountyWashington541,188472,08114.64%
Summit CountyOhio540,333541,645-0.24%
Montgomery CountyOhio531,861535,597-0.70%
Kane CountyIllinois531,769516,0683.04%
Chester CountyPennsylvania530,795499,9256.17%
Adams CountyColorado529,555443,69119.35%
Plymouth CountyMassachusetts526,762495,9266.22%
Sedgwick CountyKansas521,158499,1284.41%
Ada CountyIdaho507,233393,35428.95%
Camden CountyNew Jersey506,707513,275-1.28%
Clark CountyWashington501,869426,70417.62%
Passaic CountyNew Jersey499,112502,023-0.58%
Polk CountyIowa498,817432,35215.37%
Pinal CountyArizona494,755379,09430.51%
Morris CountyNew Jersey489,395492,617-0.65%
Lake CountyIndiana487,599495,947-1.68%
Washoe CountyNevada485,849421,95415.14%
Sonoma CountyCalifornia485,722484,7550.20%
Seminole CountyFlorida479,234423,05113.28%
Prince William CountyVirginia478,535406,16917.82%
Knox CountyTennessee478,423432,93810.51%
Richmond CountyNew York475,909469,6151.34%
Tulare CountyCalifornia469,407442,9695.97%
Hampden CountyMassachusetts462,340464,237-0.41%
Onondaga CountyNew York458,286467,533-1.98%
York CountyPennsylvania451,480435,4133.69%
Solano CountyCalifornia451,479413,9679.06%
Virginia Beach cityVirginia450,224438,8592.59%
Sarasota CountyFlorida448,568379,93018.07%
Santa Barbara CountyCalifornia447,937424,2315.59%
Burlington CountyNew Jersey446,557449,129-0.57%
Dakota CountyMinnesota436,983399,2119.46%
East Baton Rouge ParishLouisiana436,061440,912-1.10%
Monterey CountyCalifornia434,283416,3734.30%
Jefferson ParishLouisiana429,711432,610-0.67%
Loudoun CountyVirginia429,570315,47836.16%
Lucas CountyOhio425,820441,434-3.54%
Cameron CountyTexas425,211407,6304.31%
Clackamas CountyOregon423,729376,78812.46%
Berks CountyPennsylvania422,434412,0392.52%
Hillsborough CountyNew Hampshire421,815401,0555.18%
Charleston CountySouth Carolina421,774350,94020.18%
Manatee CountyFlorida420,985323,42430.17%
Richland CountySouth Carolina418,873385,7358.59%
Mobile CountyAlabama411,814413,315-0.36%
Placer CountyCalifornia410,327350,02117.23%
St. Charles CountyMissouri408,506361,80312.91%
Waukesha CountyWisconsin407,550390,0284.49%
Genesee CountyMichigan404,063424,953-4.92%
Collier CountyFlorida398,304322,58123.47%
Pulaski CountyArkansas391,897383,5382.18%
Orange CountyNew York390,568373,4454.59%
Osceola CountyFlorida390,341269,83744.66%
Lane CountyOregon389,103351,92010.57%
Forsyth CountyNorth Carolina388,453351,37410.55%
Orleans ParishLouisiana388,424347,77211.69%
Lake CountyFlorida387,914297,70930.30%
Allen CountyIndiana387,739355,9458.93%
Butler CountyOhio385,402369,1024.42%
Brazoria CountyTexas385,018314,42822.45%
Madison CountyAlabama384,719336,09514.47%
Marion CountyFlorida378,613331,33114.27%
Bell CountyTexas377,978312,84920.82%
Hamilton CountyTennessee374,826337,21411.15%
Horry CountySouth Carolina374,033270,27438.39%
Lehigh CountyPennsylvania371,236350,1646.02%
Larimer CountyColorado369,377300,44122.94%
Stark CountyOhio369,322375,372-1.61%
Douglas CountyColorado367,484286,97728.05%
Mercer CountyNew Jersey365,914367,713-0.49%

Counties in the United States by Population 2021