Hamilton County vs Marion County
Two neighbouring counties in Indiana, compared on population, size, income and housing. They share 16 mi of border.
Hamilton County
Indiana
Marion County
Indiana
Both outlines are drawn at true relative size. Marion County spans about 36.3 km at its widest.
Side by side
| Measure | Hamilton County | Difference | Marion County |
|---|---|---|---|
| Population | 387,036 | -61.0% | 992,196 |
| Change since 2020 | 10.9% | +9.3 pp | 1.6% |
| Land area | 394.4 sq mi | -0.4% | 396 sq mi |
| Population density | 981 per sq mi | -60.9% | 2,506 per sq mi |
| Median household income | $121,530 | +83.2% | $66,346 |
| Median home value | $405,500 | +81.0% | $224,000 |
| Median age | 38.4 | +11.6% | 34.4 |
| Households | 137,252 | -65.7% | 400,432 |
| Housing units | 144,746 | -67.2% | 441,040 |
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; US Census Bureau, County Adjacency File, 2025 County Adjacency File, released 15 September 2025. The difference column is computed here: the first county's figure against the second, expressed as a percentage of the second. The change-since-2020 row is the exception: two growth rates differ in percentage points (pp), not percent. Retrieved 30 August 2026.
What the numbers say
- Marion County holds about 2.6 times the population of Hamilton County: 992,196 against 387,036.
- Marion County covers more ground, at 396 square miles against 394.4.
- Marion County is the more crowded of the two, at 2,506 people per square mile against 981.
- Median household income is higher in Hamilton County, by 55,184 dollars a year.
- Since 2020, Hamilton County has grown by 10.9% and Marion County has grown by 1.6%.
- They share 16 mi of common border, which the Census Bureau publishes in its county adjacency file and which almost no other county reference presents.
Full pages
Want a different pair? Compare any two of the 3,144 US counties.
Rebuilt from source data 30 August 2026. How these figures are produced.