Montgomery County, Pennsylvania
A county in Pennsylvania, ranked 3 of 67 by population.
CountyFIPS 42091
- Population
- 877,643
- +20,814 (+2.4%) since 2020
- Land area
- 482.9
- square miles. A further 0.9% of the total area is water
- Population density
- 1,817
- people per square mile, computed rather than published
- County seat
- Norristown
- Seat of county government.
- Established
- 1784
- 241 years ago
- Largest city
- Norristown borough
- Population 35,911.
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 Montgomery 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.
Where Montgomery County ranks
Position among the 67 counties of Pennsylvania, and among all 3,144 US counties and county-equivalents. Computed from the figures on this page.
| Measure | Value | In Pennsylvania | Nationally |
|---|---|---|---|
| Population | 877,643 | 3rd of 67 | 71st of 3,144 |
| Land area | 482.9 sq mi | 47th of 67 | 2,144th of 3,144 |
| Population density | 1,817 per sq mi | 3rd of 67 | 81st of 3,144 |
| Median household income | $113,915 | 3rd of 67 | 75th of 3,143 |
Full data for Montgomery County
| Measure | Value | Source and vintage |
|---|---|---|
| Population | 877,643 | Vintage 2025 Population Estimates |
| Population in 2020 | 856,829 | Vintage 2025 Population Estimates |
| 2020 estimates base? | 856,392 | Vintage 2025 Population Estimates |
| Land area | 482.9 sq mi | 2025 Gazetteer Files |
| Water area | 4.2 sq mi | 2025 Gazetteer Files |
| Total area | 487.2 sq mi | 2025 Gazetteer Files |
| Population density? | 1,817 per sq mi | Computed: Vintage 2025 estimates divided by 2025 Gazetteer land area |
| Median household income | $113,915 | American Community Survey 2020-2024 5-Year Estimates |
| Median home value | $436,700 | American Community Survey 2020-2024 5-Year Estimates |
| Median age | 41.2 | American Community Survey 2020-2024 5-Year Estimates |
| Households | 335,505 | American Community Survey 2020-2024 5-Year Estimates |
| Housing units | 350,351 | American 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
- +442
- 8,325 births, 7,883 deaths
- Net migration
- +1,993
- 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 Montgomery 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 area | State | Shared border | Population |
|---|---|---|---|
| Chester County | Pennsylvania | 34 mi | 557,116 |
| Bucks County | Pennsylvania | 31 mi | 647,828 |
| Philadelphia County | Pennsylvania | 29 mi | 1,574,281 |
| Berks County | Pennsylvania | 17 mi | 440,072 |
| Delaware County | Pennsylvania | 8.2 mi | 580,937 |
| Lehigh County | Pennsylvania | 3.1 mi | 384,383 |
Source: US Census Bureau, County Adjacency File, 2025 County Adjacency File, released 15 September 2025. Retrieved 30 August 2026.
Side by side
All 67 counties of Pennsylvania
Open the interactive Pennsylvania county map, or jump straight to any of them.
- Adams County
- Allegheny County
- Armstrong County
- Beaver County
- Bedford County
- Berks County
- Blair County
- Bradford County
- Bucks County
- Butler County
- Cambria County
- Cameron County
- Carbon County
- Centre County
- Chester County
- Clarion County
- Clearfield County
- Clinton County
- Columbia County
- Crawford County
- Cumberland County
- Dauphin County
- Delaware County
- Elk County
- Erie County
- Fayette County
- Forest County
- Franklin County
- Fulton County
- Greene County
- Huntingdon County
- Indiana County
- Jefferson County
- Juniata County
- Lackawanna County
- Lancaster County
- Lawrence County
- Lebanon County
- Lehigh County
- Luzerne County
- Lycoming County
- McKean County
- Mercer County
- Mifflin County
- Monroe County
- Montgomery County
- Montour County
- Northampton County
- Northumberland County
- Perry County
- Philadelphia County
- Pike County
- Potter County
- Schuylkill County
- Snyder County
- Somerset County
- Sullivan County
- Susquehanna County
- Tioga County
- Union County
- Venango County
- Warren County
- Washington County
- Wayne County
- Westmoreland County
- Wyoming County
- York County
Data on this page last rebuilt 30 August 2026. How these figures are produced.