County Maps US

Franklin County, Missouri

A county in Missouri, ranked 12 of 115 by population.

CountyFIPS 29071

Within Missouri
Franklin County, highlighted, with the areas around it. Boundaries generalised from the 2025 Census cartographic boundary file; neighbour fills carry no data. The dot marks Union, the county seat, located via the 2025 Census Gazetteer.

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Population
108,090
+3,238 (+3.1%) since 2020
Land area
922.5
square miles. A further 0.9% of the total area is water
Population density
117
people per square mile, computed rather than published
County seat
Union
Seat of county government.
Established
1818
207 years ago
Largest city
Washington city
Population 15,906.

Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025; Wikidata (CC0), Wikidata. Retrieved 30 August 2026.

Satellite view

Aerial imagery of Franklin County with its boundary drawn on top. A map shows you the shape; this shows you what is inside it, and which side of the line a place falls on.

Aerial view of Franklin County, Missouri from the USGS National Map, with its boundary outlined
Imagery: USGS National Map, USGS Imagery Only, public domain, requested from USGS by your browser when you reach this point on the page, at 791 by 800 pixels. The boundary is the 2025 Census cartographic boundary file, reprojected to Web Mercator to match the imagery. You can also open the USGS National Map viewer.

Where Franklin County ranks

Position among the 115 counties of Missouri, and among all 3,144 US counties and county-equivalents. Computed from the figures on this page.

MeasureValueIn MissouriNationally
Population108,09012th of 115583rd of 3,144
Land area922.5 sq mi4th of 115792nd of 3,144
Population density117 per sq mi17th of 115810th of 3,144
Median household income$73,16516th of 115959th of 3,143

Full data for Franklin County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population108,090Vintage 2025 Population Estimates
Population in 2020104,852Vintage 2025 Population Estimates
2020 estimates base?104,680Vintage 2025 Population Estimates
Land area922.5 sq mi2025 Gazetteer Files
Water area8.1 sq mi2025 Gazetteer Files
Total area930.6 sq mi2025 Gazetteer Files
Population density?117 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$73,165American Community Survey 2020-2024 5-Year Estimates
Median home value$227,600American Community Survey 2020-2024 5-Year Estimates
Median age41.8American Community Survey 2020-2024 5-Year Estimates
Households43,036American Community Survey 2020-2024 5-Year Estimates
Housing units46,312American Community Survey 2020-2024 5-Year Estimates

Sources: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026; US Census Bureau, Gazetteer Files, 2025 Gazetteer Files, released 10 September 2025; US Census Bureau, American Community Survey, American Community Survey 2020-2024 5-Year Estimates, released 29 January 2026. Population density is computed here, not published: it divides the Vintage 2025 population estimate by the 2025 Gazetteer land area, which are two different Census products. Retrieved 30 August 2026.

How the population changed

The Census Bureau publishes the components behind an estimate, not just the total. For the year to July 2025:

Births minus deaths
-42
1,124 births, 1,166 deaths
Net migration
+740
More people moved in than moved out.

Source: US Census Bureau, Population Estimates Program, Vintage 2025 Population Estimates, released 26 March 2026. Retrieved 30 August 2026.

The 7 areas bordering Franklin County

Ordered by the length of the border actually shared, which the Census Bureau publishes in its county adjacency file and which no other county reference presents.

Bordering areaStateShared borderPopulation
Gasconade CountyMissouri34 mi14,784
Warren CountyMissouri28 mi39,016
Jefferson CountyMissouri18 mi233,132
Washington CountyMissouri17 mi23,810
St. Charles CountyMissouri16 mi426,499
Crawford CountyMissouri15 mi22,929
St. Louis CountyMissouri12 mi990,911

Source: US Census Bureau, County Adjacency File, 2025 County Adjacency File, released 15 September 2025. Retrieved 30 August 2026.

All 115 counties of Missouri

Open the interactive Missouri county map, or jump straight to any of them.

Data on this page last rebuilt 30 August 2026. How these figures are produced.