• county
  • FIPS 39159
  • Largest town: Marysville

Union County, Ohio

Union County had 71,721 residents in the Census Vintage 2024 estimate, on 431.7 square miles of land. It ranks 36th of 88 in Ohio by population and 45th by land area.

Population
71,721
#36 of 88 in Ohio · #771 in US
Area
431.7 sq mi
#45 of 88 in Ohio · #2,351 in US
Density
166 / sq mi
#30 of 88 in Ohio · #638 in US
Median household income
$104,592
#3 of 88 in Ohio · #93 in US

Census Vintage 2024 estimates · SAIPE 2023 income · 2024 Gazetteer land area

Union County within Ohio. Pin: Columbus.

Measure from here

Tools and pages that start from Union County

Union County population, land area and income

Union County had 71,721 residents in the Census Vintage 2024 estimate, on 431.7 square miles of land. It ranks 36th of 88 in Ohio by population and 45th by land area. That works out to 166.1 people per square mile, 1.7 times the US average of 96.3, and in the top quarter nationally.

The median county-equivalent in Ohio has 58,250 residents; Union County is somewhat larger.

Its SAIPE 2023 median household income of $104,592 is in the top tenth among 3,143 counties with an estimate.

National rank among 3,144

Population

71,721

3144th1st

771st of 3,144 (US)

Land area

432 sq mi

3144th1st

2351st of 3,144 (US)

Density

166.1 / sq mi

3144th1st

638th of 3,144 (US)

Median household income

$104,592

3143rd1st

93rd of 3,143 (US)

Rank within Ohio (88)

Population

71,721

88th1st

36th of 88 (OH)

Land area

432 sq mi

88th1st

45th of 88 (OH)

Density

166.1 / sq mi

88th1st

30th of 88 (OH)

Median household income

$104,592

88th1st

3rd of 88 (OH)

How Union County's population changed since 2020

Union County gained 8,631 residents between the July 2020 and July 2024 estimates, a rise of 13.7%. That ranks 1st of 88 in Ohio for growth. The median Ohio county changed by -0.2%, and the state as a whole by +0.7%.

Since the April 2020 estimates base, Union County recorded 3,038 births and 2,181 deaths, a natural change of +857. Net international migration added +683 and net domestic migration, people moving to or from other US counties, came to +7,385. The largest single component was domestic migration, which added 7,385 people.

63.1k202065.1k202166.9k202269.8k202371.7k2024
Census Vintage 2024 county estimates for July 1 of each year. The axis starts above zero so year-to-year changes are visible.

Components of change, April 2020 to July 2024

Births
3,038
Deaths
2,181
Net international migration
+683
Net domestic migration
+7,385
Change, July 2023 to July 2024
+1,956

Where Union County is

The Census internal point of Union County is at 40.295900, -83.367000. It sits in UTM zone 17N. The map shades Ohio's 88 county-equivalents by population change from 2020 to 2024, darker for faster growth, with Union County outlined. Dots are towns of 1,000+ people with residents in it.

Shelby County: -0.4%Defiance County: +1.0%Darke County: -0.8%Seneca County: -0.6%Wood County: +0.6%Fayette County: -0.7%Clark County: -0.7%Hocking County: -2.2%Jackson County: +0.2%Miami County: +2.7%Richland County: -0.1%Union County: +13.7%Auglaize County: -1.2%Hancock County: +0.1%Morgan County: -1.6%Van Wert County: -0.1%Hardin County: -1.0%Paulding County: -0.3%Portage County: +1.2%Delaware County: +10.6%Harrison County: -3.1%Ross County: -1.3%Crawford County: -0.9%Clinton County: -0.0%Henry County: -0.5%Pike County: -0.0%Cuyahoga County: -1.7%Highland County: +1.0%Knox County: +1.7%Ottawa County: -1.5%Huron County: -0.6%Erie County: -2.2%Holmes County: +1.0%Lawrence County: -4.0%Marion County: -0.6%Fairfield County: +5.2%Putnam County: -0.6%Guernsey County: -0.5%Vinton County: -2.1%Gallia County: -1.2%Trumbull County: -0.7%Wayne County: -0.2%Perry County: +0.6%Ashland County: -0.1%Fulton County: -1.4%Brown County: +1.4%Lucas County: -1.1%Stark County: -0.1%Medina County: +1.1%Belmont County: -2.4%Williams County: -1.4%Mahoning County: -1.0%Noble County: +1.1%Greene County: +2.5%Preble County: -0.5%Allen County: -1.2%Athens County: +1.3%Jefferson County: -2.0%Adams County: +0.8%Monroe County: -2.3%Washington County: -2.2%Logan County: -0.1%Franklin County: +2.4%Warren County: +5.3%Wyandot County: -2.1%Licking County: +3.4%Hamilton County: +0.8%Clermont County: +2.6%Butler County: +2.2%Coshocton County: +1.1%Geauga County: -0.0%Sandusky County: -0.0%Ashtabula County: -0.6%Carroll County: -0.9%Tuscarawas County: -1.2%Morrow County: +2.7%Montgomery County: +0.1%Mercer County: +0.3%Lake County: -0.1%Pickaway County: +6.0%Madison County: +3.8%Muskingum County: +0.1%Meigs County: -3.0%Columbiana County: -1.8%Lorain County: +2.7%Scioto County: -2.8%Champaign County: +0.4%Summit County: -0.3%
Change 2020 to 2024
  1. < -1.4%
  2. < -0.6%
  3. < -0.0%
  4. < +1.1%
  5. ≥ +1.1%
no data

Orange pin: Union County internal point. Dark pin: Columbus.

Internal point

Decimal
40.295900, -83.367000
DMS
40°17'45.24"N 83°22'1.20"W
UTM
17N 298818.9E 4463288.5N
Geohash
dphtnzwh8
Plus code
86GR7JWM+95

Towns in Union County

4 incorporated places of 1,000+ people have residents in Union County, 36,966 people together, or 52% of the county. Each figure counts only the part of the town inside Union County; towns marked "part" extend into another county. The largest is Marysville with 29,276.

  1. 01Marysville29,276
  2. 02Dublin (part)4,361
  3. 03Richwood2,575
  4. 04Plain City (part)754
Census Vintage 2024 subcounty estimates, county parts of incorporated places (SUMLEV 157).

Counties bordering Union County

The Census 2024 county adjacency file lists 7 neighbors for Union County. The most populous is Franklin County, OH, with 1,356,303 residents. Distances run between Census internal points in a straight line.

Distance to Columbus and the nearest big city

Columbus is 30.1 miles SE of Union County's internal point in a straight line. The nearest place of 100,000 or more is Columbus, OH (population 933,263), 29.5 miles away. The nearest place of 10,000 or more is Marysville, OH (population 29,276), 4.7 miles away.

Union County FIPS code

The FIPS code of Union County is 39159: state code 39 for Ohio plus county code 159. Use it as text, with the leading zero, when joining Census, BLS, or CDC county tables. SAIPE lists its 2023 median household income as $104,592.

Questions people ask

What is the population of Union County, Ohio?

The Census Vintage 2024 estimate for July 1, 2024 is 71,721. That is up 8,631 people (13.7%) from the July 2020 estimate of 63,090.

What is the FIPS code of Union County?

39159. The first two digits (39) are Ohio; the last three (159) identify the county.

What is the largest town in Union County?

Marysville, with 29,276 residents inside Union County in 2024.

Which counties border Union County?

7 county-equivalents border it in the Census 2024 adjacency file: Franklin County, OH; Delaware County, OH; Marion County, OH; Logan County, OH; Madison County, OH; Champaign County, OH; Hardin County, OH.

Sources and data as of

Data as of: Census Vintage 2024 population estimates, 2024 Gazetteer land area and internal points, SAIPE 2023 median household income.

  1. 01Census Vintage 2024 county population estimates
  2. 02Census 2024 Gazetteer, counties
  3. 03Census SAIPE 2023 state and county estimates
  4. 04Census Vintage 2024 subcounty population estimates
  5. 05Census 2024 county adjacency file
  6. 06Census 2024 cartographic boundary file, counties (1:5,000,000)

How every number is computed: methodology. Spotted a wrong figure? Report an error.