County · code 56003
Big Horn CountyWyoming
Big Horn County is a Wyoming county covering 3,137 square miles, with its seat in Basin. The county was named after the Big Horn Mountains.
- Founded1890
- County seatBasin
- Named forBig Horn Mountains, Wyoming and Montana
- Land area3,137 sq mi + 21 sq mi water
- Population11,521 2020 Census
- Parcels mapped8,483 checked 14 October 2026
Where it is
Big Horn on the map of Wyoming
Wyoming has 23 counties and county equivalents, each with its own records office. Shapes with a page are links.
History
Formed in 1890 from Fremont County, Johnson County and Sheridan County
An old deed may name a county that no longer exists, or a boundary that has since moved.
Big Horn County was created on March 12, 1890 by Wyoming Territory from parts of Fremont, Johnson, and Sheridan counties, though it was initially attached to those counties for judicial, revenue, and election purposes. The county became fully organized on January 4, 1897, when it was detached from Fremont, Johnson, and Sheridan. Big Horn subsequently contributed territory to the creation of Park County in 1909 and Hot Springs and Washakie counties in 1911.
- 1890Big Horn County created Big Horn created by Wyoming Territory from Fremont, Johnson, and Sheridan; Big Horn not fully organized, attached to Fremont, Johnson, and Sheridan "for judicial, revenue and election purposes." · Wyo. Terr. Laws 1890, 11th leg., ch. 48/pp. 80-83
- 1890Became part of Wyoming Big Horn became a county in the state of Wyoming. · Wyoming Constitution 1889, art. 12 in Swindler, 10:493; U.S. Stat., vol. 26, ch. 664[1890]/pp. 222-226; Van Zandt, 145
- 1897
- 1909Lost territory Big Horn lost to creation of Park. Park not fully organized, attached to Big Horn "for judicial, revenue and election purposes." · Wyo. Laws 1909, 10th leg., ch. 19/pp. 23-24
- 1911
- 1911Lost territory Big Horn lost to creation of Hot Springs and Washakie. Hot Springs and Washakie not fully organized, part of Hot Springs and all of Washakie attached to Big Horn "for judicial, revenue and election purposes." Big Horn boundaries were redefined to run on federal land survey lines (no change). Technically, Hot Springs and Washakie had been created on 9 February 1911, but the several boundary laws of February 1911 were not passed in the intended sequence and mapping them in strict chronological order is not practical. By treating the law of 21 February as the basic structure that the other laws modify, the mapping reflects the intent of the legislature. · Wyo. Laws 1911, 11th leg., chs. 8-9/pp. 7-11 and ch. 77, secs. 2, 6, 9-10/pp. 102-104, 106-107, 109-110
- 1913Changed Hot Springs and Washakie fully organized, detached from Big Horn. · Trenholm, 2:518
Land and parcels
What the maps cover in Big Horn
Who publishes each layer, how good it is, and when we last checked.
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Parcels Good enough
Lot lines and tax-map numbers for 8,483 parcels from Big Horn County. Drawn for tax purposes: usually within a few feet of a survey, but not a survey.
checked 14 October 2026 -
Address points Missing
No public address points layer found for Big Horn County yet.
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Buildings Reference
Roof outlines traced from aerial imagery from FEMA Response Geospatial Office with Oak Ridge National Laboratory (ORNL). Good for seeing what is on a lot; not accurate enough to set a fence from.
checked 18 October 2026
- Official
- from the office that keeps the record
- Good enough
- a reliable statewide or national copy
- Fallback
- a guide only; check the official record
- Missing
- nothing public found yet
People and land
Big Horn by the Census
Source: US Census Bureau, 2020 Census; US Census Bureau, 2020 Gazetteer Files. Not endorsed or certified by the Census Bureau.
Rules and offices
Who to ask before you build, dig or sell
Official county pages only. We link to them; we do not copy them, because they change.
Inside a city or town, permits usually come from that city rather than the county.
Records
Zoning and code
- Planning and zoning
Land Planning - Contact Information
- Planning & Zoning
GIS and maps
County government
- County government
The official website of Big Horn County.
See your own lot on these maps
Open Big Horn County on Parcel Chart's free map and click your parcel. Save it with a free account; the full record of your place (site map, projects, documents) is Pro, in early access.
Questions
Common questions about Big Horn County
- When was Big Horn County founded?
- Big Horn County was founded in 1890, formed from Fremont County, Johnson County and Sheridan County, and named after Big Horn Mountains, Wyoming and Montana.
- What is the county seat of Big Horn County?
- The county seat of Big Horn County is Basin.
- Is there an online parcel map for Big Horn County?
- Yes. Big Horn County publishes a parcel map of 8,483 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
- Has Big Horn County's boundary or name changed?
- Big Horn County was created in 1890 from Fremont County, Johnson County and Sheridan County. Since then the Atlas of Historical County Boundaries records 5 later changes, chiefly involving Park County, Fremont County and Hot Springs County.
- Who issues building permits in Big Horn County?
- The county's page on building permits: Permits. Inside a city or town, ask that city first.
- Is my lot in a flood zone?
- We do not have flood maps for Big Horn County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.
Nearby