Summit County, Colorado
County seat: Breckenridge · Population 31,517 (2025) · 608 sq mi
Summit County is the 19th most populous of Colorado's 64 counties, with 31,517 people (2025 estimate). Its county seat is Breckenridge. It is part of the Region 12: Northern Mountains region, one of the 14 Planning and Management Regions of Colorado. The map shows its 7 cities and towns and the 5 neighboring counties.
Summit County facts
- County seat
- Breckenridge
- Population (2025 estimate)
- 31,517 +0.7% since 2020
- Land area
- 608 sq mi 55th largest of 64
- Water area
- 11 sq mi
- Population density
- 52 per sq mi
- Established
- 1861
- Same name
- One of 3 Summit Counties in the US
- Named after
- Continental Divide of the Americas principal hydrological divide of North and South America
- Largest city
- Silverthorne 5,418
- Median household income
- $109,773
- Cities and towns
- 7 plus 2 CDPs
- ZIP codes
- 4
- Time zone
- Mountain
- FIPS code
- 08117
Cities and towns in Summit County
Summit County has 7 incorporated cities, towns and villages. Populations count the people living inside Summit County; cities that cross a county line also list the other counties.
| Name | Type | Population 2025 | Also in |
|---|---|---|---|
| Silverthorne | Town | 5,418 | |
| Breckenridge (county seat) | Town | 5,015 | |
| Frisco | Town | 2,792 | |
| Keystone | Town | 1,274 | |
| Dillon | Town | 1,029 | |
| Blue River | Town | 859 | |
| Montezuma | Town | 72 |
Unincorporated communities (CDPs)
Census-designated places are communities without their own city government; the county provides their services.
| Community | Population | Also in |
|---|---|---|
| Copper Mountain | 353 | |
| Heeney | 63 |
ZIP codes in Summit County
4 ZIP codes reach into Summit County. ZIP codes ignore county lines, so some also cover a neighboring county.
- 80424
- 80435
- 80443
- 80498 also Grand County
Population of Summit County, 2020–2025
Summit County grew by 228 people (+0.7%) between April 2020 and July 2025: 915 more births than deaths and a net loss of 745 people from migration.
| Year (July 1) | Population |
|---|---|
| 2020 | 31,237 |
| 2021 | 31,250 |
| 2022 | 31,276 |
| 2023 | 31,343 |
| 2024 | 31,643 |
| 2025 | 31,517 |
Neighboring counties
- Eagle County west · 54,291 people
- Grand County north · 16,496 people
- Park County southeast · 18,314 people
- Clear Creek County east · 8,994 people
- Lake County south · 7,552 people
Printable Summit County map
The PDF is a vector file with real text: it prints sharp on Letter paper and you can search it for a town. The PNG is 2400 pixels wide for slides and documents. Both are free to use with a credit to WhichCounty.
- PDF (Letter) (93 KB)
- PNG (2400 px) (97 KB)
Paste this code to embed the map on your site:
Sources
- Boundaries: U.S. Census Bureau, 2025 Cartographic Boundary Files (1:500,000).
- Population: Census Bureau county and city estimates, Vintage 2025. CDP populations: American Community Survey 2020–2024.
- Places and ZIP codes: Census Bureau 2026 Gazetteer and 2020 ZIP Code Tabulation Area relationship files.
- County seat, founding year and name origin: Wikidata (CC0), checked against state sources.
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