County Maps US

Buchanan County, Missouri

A county in Missouri, ranked 15 of 115 by population.

CountyFIPS 29021

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

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Population
83,540
-931 (-1.1%) since 2020
Land area
408.2
square miles. A further 1.7% of the total area is water
Population density
205
people per square mile, computed rather than published
County seat
St. Joseph
Seat of county government.
Established
1839
186 years ago
Largest city
St. Joseph city
Population 71,001.

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 Buchanan 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 Buchanan 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 800 by 613 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 Buchanan 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
Population83,54015th of 115705th of 3,144
Land area408.2 sq mi109th of 1152,475th of 3,144
Population density205 per sq mi10th of 115561st of 3,144
Median household income$62,15847th of 1151,883rd of 3,143

Full data for Buchanan County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population83,540Vintage 2025 Population Estimates
Population in 202084,471Vintage 2025 Population Estimates
2020 estimates base?84,800Vintage 2025 Population Estimates
Land area408.2 sq mi2025 Gazetteer Files
Water area6.9 sq mi2025 Gazetteer Files
Total area415.2 sq mi2025 Gazetteer Files
Population density?205 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$62,158American Community Survey 2020-2024 5-Year Estimates
Median home value$166,300American Community Survey 2020-2024 5-Year Estimates
Median age38.9American Community Survey 2020-2024 5-Year Estimates
Households33,439American Community Survey 2020-2024 5-Year Estimates
Housing units38,472American 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
-67
1,023 births, 1,090 deaths
Net migration
+10
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 6 areas bordering Buchanan 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
Doniphan CountyKansas30 mi7,594
Platte CountyMissouri27 mi114,400
Clinton CountyMissouri15 mi21,661
Andrew CountyMissouri15 mi18,241
Atchison CountyKansas8.6 mi16,172
DeKalb CountyMissouri5.0 mi9,795

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.