County Maps US

St. Johns County, Florida

A county in Florida, ranked 21 of 67 by population.

CountyFIPS 12109

Within Florida
St. Johns 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. Augustine, the county seat, located via the 2025 Census Gazetteer.

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Population
346,328
+69,209 (+25.0%) since 2020
Land area
600.7
square miles. A further 26.9% of the total area is water
Population density
577
people per square mile, computed rather than published
County seat
St. Augustine
Seat of county government.
Established
1821
204 years ago
Largest city
St. Augustine city
Population 16,141.

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 St. Johns 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 St. Johns County, Florida 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 555 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 St. Johns County ranks

Position among the 67 counties of Florida, and among all 3,144 US counties and county-equivalents. Computed from the figures on this page.

MeasureValueIn FloridaNationally
Population346,32821st of 67218th of 3,144
Land area600.7 sq mi44th of 671,623rd of 3,144
Population density577 per sq mi15th of 67252nd of 3,144
Median household income$109,8391st of 67102nd of 3,143

Full data for St. Johns County

Every figure below is attributed to the Census Bureau product it came from, with the vintage of that product.
MeasureValueSource and vintage
Population346,328Vintage 2025 Population Estimates
Population in 2020277,119Vintage 2025 Population Estimates
2020 estimates base?273,426Vintage 2025 Population Estimates
Land area600.7 sq mi2025 Gazetteer Files
Water area220.9 sq mi2025 Gazetteer Files
Total area821.5 sq mi2025 Gazetteer Files
Population density?577 per sq miComputed: Vintage 2025 estimates divided by 2025 Gazetteer land area
Median household income$109,839American Community Survey 2020-2024 5-Year Estimates
Median home value$489,200American Community Survey 2020-2024 5-Year Estimates
Median age44.2American Community Survey 2020-2024 5-Year Estimates
Households115,794American Community Survey 2020-2024 5-Year Estimates
Housing units133,504American 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
+126
2,612 births, 2,486 deaths
Net migration
+13,009
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 4 areas bordering St. Johns 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
Duval CountyFlorida34 mi1,062,963
Flagler CountyFlorida28 mi140,360
Clay CountyFlorida22 mi239,593
Putnam CountyFlorida16 mi77,734

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

All 67 counties of Florida

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

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