Jefferson County, Kentucky

The most populous of Kentucky's 120 counties.

CountyFIPS 21111

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

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Population
795,222
+12,356 (+1.6%) since 2020
Land area
380.8
square miles. A further 4.2% of the total area is water
Population density
2,088
people per square mile, computed rather than published
County seat
Louisville
Seat of county government.
Established
1780
245 years ago
Largest city
Louisville/Jefferson County metro government (balance)
Population 641,962.

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 Jefferson 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 Jefferson County, Kentucky 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 728 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 Jefferson County ranks

Position among the 120 counties of Kentucky, and among all 3,144 US counties and county-equivalents. Computed from the figures on this page.

MeasureValueIn KentuckyNationally
Population795,2221st of 12083rd of 3,144
Land area380.8 sq mi38th of 1202,600th of 3,144
Population density2,088 per sq mi1st of 12068th of 3,144
Median household income$69,86613th of 1201,205th of 3,143

Full data for Jefferson County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population795,222Vintage 2025 Population Estimates
Population in 2020782,866Vintage 2025 Population Estimates
2020 estimates base?782,962Vintage 2025 Population Estimates
Land area380.8 sq mi2025 Gazetteer Files
Water area16.8 sq mi2025 Gazetteer Files
Total area397.6 sq mi2025 Gazetteer Files
Population density?2,088 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$69,866American Community Survey 2020-2024 5-Year Estimates
Median home value$248,400American Community Survey 2020-2024 5-Year Estimates
Median age38.4American Community Survey 2020-2024 5-Year Estimates
Households331,554American Community Survey 2020-2024 5-Year Estimates
Housing units359,710American 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
+1,505
9,974 births, 8,469 deaths
Net migration
-384
More people moved out than moved in.

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

The 8 areas bordering Jefferson 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
Bullitt CountyKentucky32 mi86,454
Clark CountyIndiana14 mi130,451
Harrison CountyIndiana13 mi40,437
Oldham CountyKentucky13 mi70,986
Shelby CountyKentucky12 mi51,243
Floyd CountyIndiana10 mi82,153
Spencer CountyKentucky2.0 mi20,998
Hardin CountyKentucky0.7 mi113,482

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

All 120 counties of Kentucky

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

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