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 CountyCalifornia10,079,0009,822,4302.61%
Cook CountyIllinois5,132,4805,199,170-1.28%
Harris CountyTexas4,767,5404,107,83016.06%
Maricopa CountyArizona4,573,3103,825,19019.56%
San Diego CountyCalifornia3,379,1603,103,3108.89%
Orange CountyCalifornia3,198,0003,016,5606.01%
Miami-Dade CountyFlorida2,794,9902,507,06011.48%
Dallas CountyTexas2,667,7202,372,33012.45%
Kings CountyNew York2,555,7202,509,8801.83%
Riverside CountyCalifornia2,517,8302,201,65014.36%
Clark CountyNevada2,328,3201,952,64019.24%
King CountyWashington2,291,0301,938,38018.19%
Queens CountyNew York2,242,9902,234,7400.37%
San Bernardino CountyCalifornia2,208,4002,040,9108.21%
Tarrant CountyTexas2,139,8601,817,51017.74%
Bexar CountyTexas2,040,4601,722,86018.43%
Broward CountyFlorida1,984,8401,752,83013.24%
Santa Clara CountyCalifornia1,945,9401,786,0808.95%
Wayne CountyMichigan1,749,1501,815,160-3.64%
Alameda CountyCalifornia1,684,0001,513,04011.30%
Middlesex CountyMassachusetts1,634,1501,507,6908.39%
New York CountyNew York1,626,5401,588,7602.38%
Philadelphia CountyPennsylvania1,591,9701,528,2904.17%
Sacramento CountyCalifornia1,567,4901,421,41010.28%
Palm Beach CountyFlorida1,517,1501,323,65014.62%
Hillsborough CountyFlorida1,490,4301,233,49020.83%
Suffolk CountyNew York1,476,1401,494,380-1.22%
Orange CountyFlorida1,436,0701,148,59025.03%
Bronx CountyNew York1,416,9501,387,3502.13%
Nassau CountyNew York1,359,7001,341,6901.34%
Franklin CountyOhio1,339,4901,166,26014.85%
Travis CountyTexas1,290,6901,030,54025.24%
Hennepin CountyMinnesota1,281,7901,154,19011.06%
Oakland CountyMichigan1,265,2401,203,1205.16%
Cuyahoga CountyOhio1,234,8301,278,100-3.39%
Allegheny CountyPennsylvania1,214,0401,223,970-0.81%
Salt Lake CountyUtah1,182,2601,032,98014.45%
Contra Costa CountyCalifornia1,160,9201,052,56010.29%
Fairfax CountyVirginia1,158,6201,086,1306.67%
Wake CountyNorth Carolina1,133,140906,88224.95%
Mecklenburg CountyNorth Carolina1,127,080923,25822.08%
Collin CountyTexas1,072,650788,43136.05%
Fulton CountyGeorgia1,072,570925,65115.87%
Pima CountyArizona1,062,220981,6538.21%
Montgomery CountyMaryland1,061,210976,2878.70%
Fresno CountyCalifornia1,010,120932,0638.37%
St. Louis CountyMissouri997,539998,843-0.13%
Pinellas CountyFlorida987,230916,4247.73%
Duval CountyFlorida975,259865,63712.66%
Honolulu CountyHawaii967,382956,2961.16%
Marion CountyIndiana966,106904,6026.80%
Westchester CountyNew York964,278950,6311.44%
Gwinnett CountyGeorgia947,037808,04917.20%
Fairfield CountyConnecticut944,555919,3302.74%
Milwaukee CountyWisconsin943,427948,301-0.51%
Bergen CountyNew Jersey942,938906,3414.04%
Shelby CountyTennessee935,346928,4480.74%
DuPage CountyIllinois924,443918,0290.70%
Erie CountyNew York921,569919,1430.26%
Pierce CountyWashington919,495795,39315.60%
Kern CountyCalifornia912,316841,0728.47%
Prince George's CountyMaryland910,322865,7475.15%
Denton CountyTexas906,532666,76835.96%
Hartford CountyConnecticut892,229895,226-0.33%
San Francisco CountyCalifornia891,583805,55010.68%
Hidalgo CountyTexas881,171779,21313.08%
Macomb CountyMichigan880,325841,3554.63%
New Haven CountyConnecticut857,272863,382-0.71%
Ventura CountyCalifornia851,297825,1303.17%
El Paso CountyTexas841,184803,6554.67%
Worcester CountyMassachusetts840,659800,4015.03%
Snohomish CountyWashington838,625715,50717.21%
Montgomery CountyPennsylvania836,688800,9074.47%
Middlesex CountyNew Jersey833,687810,6662.84%
Fort Bend CountyTexas831,302590,26040.84%
Baltimore CountyMaryland828,087806,5602.67%
Hamilton CountyOhio820,710802,2632.30%
Suffolk CountyMassachusetts818,846725,81912.82%
Multnomah CountyOregon818,078737,29110.96%
Essex CountyNew Jersey807,485784,0622.99%
Oklahoma CountyOklahoma803,352720,78711.45%
Essex CountyMassachusetts801,594745,4797.53%
Lee CountyFlorida784,818620,45426.49%
San Joaquin CountyCalifornia772,948687,15612.49%
San Mateo CountyCalifornia771,019719,7257.13%
Jefferson CountyKentucky770,797742,0503.87%
DeKalb CountyGeorgia765,498692,47110.55%
Cobb CountyGeorgia765,029689,52810.95%
Polk CountyFlorida752,367603,12824.74%
Monroe CountyNew York742,550744,594-0.27%
El Paso CountyColorado739,968626,90418.04%
Denver CountyColorado738,598603,35422.42%
District of ColumbiaDistrict of Columbia715,983605,08518.33%
Norfolk CountyMassachusetts713,530673,0396.02%
Jackson CountyMissouri705,481674,8244.54%
Davidson CountyTennessee699,749627,75311.47%
Lake CountyIllinois696,484704,192-1.09%
Will CountyIllinois694,896678,8182.37%
Hudson CountyNew Jersey682,339635,6347.35%
Bernalillo CountyNew Mexico678,731663,9482.23%
Arapahoe CountyColorado665,381574,76215.77%
Kent CountyMichigan662,896602,9839.94%
Jefferson CountyAlabama658,808658,1580.10%
Utah CountyUtah653,633519,99425.70%
Tulsa CountyOklahoma651,626605,0087.71%
Providence CountyRhode Island638,736627,8141.74%
Bucks CountyPennsylvania630,529625,4050.82%
Montgomery CountyTexas628,483459,21036.86%
Monmouth CountyNew Jersey619,408630,480-1.76%
Brevard CountyFlorida614,017543,97212.88%
Ocean CountyNew Jersey614,013577,5746.31%
Washington CountyOregon610,757531,64514.88%
Johnson CountyKansas610,097545,66511.81%
Williamson CountyTexas608,261426,28442.69%
Jefferson CountyColorado589,065535,8339.93%
Baltimore cityMaryland587,803621,005-5.35%
Anne Arundel CountyMaryland584,909539,2778.46%
Douglas CountyNebraska579,494518,57011.75%
Bristol CountyMassachusetts570,924549,1773.96%
Pasco CountyFlorida568,848465,48622.21%
Delaware CountyPennsylvania567,279558,9821.48%
Volusia CountyFlorida566,254494,44514.52%
New Castle CountyDelaware565,167538,7504.90%
Union CountyNew Jersey563,655537,5004.87%
Ramsey CountyMinnesota559,594509,3899.86%
Stanislaus CountyCalifornia558,911515,1658.49%
Dane CountyWisconsin553,532489,20013.15%
Lancaster CountyPennsylvania548,563520,3225.43%
Summit CountyOhio542,270541,6460.12%
Guilford CountyNorth Carolina542,018489,58910.71%
Kane CountyIllinois536,336516,1443.91%
Montgomery CountyOhio533,655535,587-0.36%
Spokane CountyWashington532,037472,08912.70%
Greenville CountySouth Carolina529,535452,67216.98%
Chester CountyPennsylvania528,270499,9245.67%
Adams CountyColorado526,748443,69818.72%
Plymouth CountyMassachusetts524,458495,9305.75%
Sedgwick CountyKansas514,243499,1273.03%
Camden CountyNew Jersey508,548513,460-0.96%
Passaic CountyNew Jersey502,542502,0550.10%
Polk CountyIowa499,440432,36215.51%
Clark CountyWashington496,587426,70916.38%
Ada CountyIdaho496,128393,35026.13%
Morris CountyNew Jersey494,234492,6630.32%
Sonoma CountyCalifornia493,334484,7761.77%
Lake CountyIndiana483,701495,939-2.47%
Washoe CountyNevada482,539421,95814.36%
Seminole CountyFlorida479,024423,05713.23%
Richmond CountyNew York477,505469,6211.68%
Pinal CountyArizona477,186379,54725.73%
Prince William CountyVirginia476,931406,17117.42%
Hampden CountyMassachusetts474,682464,2562.25%
Knox CountyTennessee474,003432,9479.48%
Tulare CountyCalifornia471,389442,9946.41%
Onondaga CountyNew York461,845467,527-1.22%
York CountyPennsylvania453,375435,4034.13%
Solano CountyCalifornia452,076413,9449.21%
Virginia Beach cityVirginia450,643438,8552.69%
Santa Barbara CountyCalifornia448,369424,2355.69%
Burlington CountyNew Jersey445,760449,124-0.75%
Sarasota CountyFlorida440,776379,93716.01%
Monterey CountyCalifornia435,828416,3964.67%
East Baton Rouge ParishLouisiana435,654440,559-1.11%
Dakota CountyMinnesota432,627399,2068.37%
Jefferson ParishLouisiana429,561432,608-0.70%
Lucas CountyOhio427,631441,437-3.13%
Loudoun CountyVirginia426,560315,47935.21%
Berks CountyPennsylvania425,408412,0253.25%
Cameron CountyTexas425,362407,6544.34%
Clackamas CountyOregon422,583376,79012.15%
Richland CountySouth Carolina420,786385,7579.08%
Hillsborough CountyNew Hampshire419,427401,0494.58%
Charleston CountySouth Carolina414,239350,96318.03%
Manatee CountyFlorida413,665323,42727.90%
Mobile CountyAlabama412,241413,319-0.26%
Placer CountyCalifornia408,317350,02616.65%
Waukesha CountyWisconsin407,076390,0204.37%
St. Charles CountyMissouri407,056361,79812.51%
Genesee CountyMichigan405,330424,951-4.62%
Osceola CountyFlorida398,648269,84147.73%
Pulaski CountyArkansas390,808383,5761.89%
Collier CountyFlorida390,774322,59521.13%
Orleans ParishLouisiana389,942347,77012.13%
Lane CountyOregon387,599351,92310.14%
Orange CountyNew York386,247373,4533.43%
Forsyth CountyNorth Carolina385,849351,3939.81%
Butler CountyOhio385,448369,1014.43%
Brazoria CountyTexas385,200314,44722.50%
Allen CountyIndiana381,633355,9397.22%
Lake CountyFlorida379,311297,70827.41%
Madison CountyAlabama376,227336,09311.94%
Washtenaw CountyMichigan374,473345,6588.34%
Lehigh CountyPennsylvania373,558350,1646.68%
Marion CountyFlorida372,497331,34012.42%
Mercer CountyNew Jersey372,229367,7441.22%
Bell CountyTexas371,224312,85018.66%
Hamilton CountyTennessee370,594337,2219.90%
Stark CountyOhio370,568375,365-1.28%
Horry CountySouth Carolina367,139270,25735.85%
Nueces CountyTexas364,767340,2537.20%