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County · code 56037

Sweetwater CountyWyoming

Sweetwater County is in Wyoming and was originally formed as Carter County on December 27, 1867. It was created from Laramie County and later renamed to Sweetwater in 1869.

  • Founded1867
  • County seatGreen River
  • Named forSweetwater River
  • Land area10,427 sq mi + 64 sq mi water
  • Population42,272 2020 Census
  • Parcels mapped27,394 checked 15 October 2026
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Updated

Daggett, UTMoffat, COFremontSubletteUintaLincolnCarbonSummit, UT Green River Census outline · seat marked

Where it is

Sweetwater on the map of Wyoming

Wyoming has 23 counties and county equivalents, each with its own records office. Shapes with a page are links.

Albany CountyBig Horn CountyCampbell CountyCarbon CountyConverse CountyCrook CountyFremont CountyGoshen CountyHot Springs CountyJohnson CountyLaramie CountyLincoln CountyNatrona CountyNiobrara CountyPark CountyPlatte CountySheridan CountySublette CountyTeton CountyUinta CountyWashakie CountyWeston CountySweetwater County Sweetwater
Counties of Wyoming · Sweetwater highlighted

History

Formed in 1867 from Laramie County

An old deed may name a county that no longer exists, or a boundary that has since moved.

Carter County was created by Dakota Territory from Laramie County on December 27, 1867, and included a small area of present Montana. It was fully organized in early 1868 and became a Wyoming Territory county in 1869 when Wyoming Territory was organized. On December 13, 1869, Carter County was renamed Sweetwater.

Boundary changes from the Newberry Library, Atlas of Historical County Boundaries; the 5 that matter most are shown first.

  1. 1867
    Sweetwater County created Carter (now Sweetwater) created by Dakota Territory from Laramie; included a small area of present Montana. Carter not fully organized, attached to Laramie "for representative and judicial purposes."
    from Laramie
    · Dak. Terr. Laws 1867, 7th sess., ch. 7/pp. 122-123
  2. 1869
    Became part of Wyoming Wyoming Territory fully organized; Carter (now Sweetwater) became a Wyoming Territory county.
    from Carter
    · Trenholm, 1:83-84, 334
  3. 1869
    Lost territory Carter (now Sweetwater) lost to creation of Uinta, implicitly exchanged non-county areas.
    to Uinta
    · Wyo. Terr. Laws 1869, 1st leg., ch. 34/p. 382; Whitehead, 194
  4. 1869
    Renamed Carter renamed Sweetwater; boundaries redefined (no change).
    formerly Carter
    · Wyo. Terr. Laws 1869, 1st leg., ch. 35/pp. 383-385; Whitehead, 194-196
  5. 1890
    Became part of Wyoming Sweetwater 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
Show all 15 changes (10 more)
  1. 1867
    Sweetwater County created Carter (now Sweetwater) created by Dakota Territory from Laramie; included a small area of present Montana. Carter not fully organized, attached to Laramie "for representative and judicial purposes."
    from Laramie
    · Dak. Terr. Laws 1867, 7th sess., ch. 7/pp. 122-123
  2. 1868
    Changed In early 1868, Carter (now Sweetwater) fully organized, detached from Laramie.
    Laramie
    · Trenholm, 1:331
  3. 1868
    Lost territory Carter (now Sweetwater) lost small area in present Montana when Wyoming Territory boundaries were defined. · Trenholm, 1:83-84; U.S. Stat., vol. 15, ch. 235[1868], secs. 1, 17/pp. 178, 183; Van Zandt, 136, 144
  4. 1869
    Became part of Wyoming Wyoming Territory fully organized; Carter (now Sweetwater) became a Wyoming Territory county.
    from Carter
    · Trenholm, 1:83-84, 334
  5. 1869
    Lost territory Carter (now Sweetwater) lost to creation of Uinta, implicitly exchanged non-county areas.
    to Uinta
    · Wyo. Terr. Laws 1869, 1st leg., ch. 34/p. 382; Whitehead, 194
  6. 1869
    Renamed Carter renamed Sweetwater; boundaries redefined (no change).
    formerly Carter
    · Wyo. Terr. Laws 1869, 1st leg., ch. 35/pp. 383-385; Whitehead, 194-196
  7. 1875
    Lost territory Sweetwater lost to creation of Pease (now Johnson). Pease not fully organized, part attached to Sweetwater "for judicial and all other purposes."
    to Peaseto Johnson
    · Whitehead, 199-201
  8. 1881
    Changed Johnson fully organized, detached from Sweetwater.
    Johnson
    · Trenholm, 1:331
  9. 1884
    Lost territory Sweetwater lost to creation of Fremont. Fremont not fully organized, attached to Sweetwater "for judicial and all other purposes."
    to Fremont
    · Wyo. Terr. Laws 1884, 8th leg., ch. 46/pp. 66-69
  10. 1884
    Changed Fremont fully organized, detached from Sweetwater.
    Fremont
    · Trenholm, 1:331
  11. 1886
    Lost territory Sweetwater lost to Carbon.
    to Carbon
    · Wyo. Terr. Laws 1886, 9th leg., ch. 5, sec. 5/pp. 6-8
  12. 1890
    Became part of Wyoming Sweetwater 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
  13. 1909
    Exchanged territory Sweetwater exchanged with Carbon when boundary was adjusted to run on federal land survey lines.
    with Carbon
    · Wyo. Laws 1909, 10th leg., ch. 129, secs. 1, 4/pp. 174-176
  14. 1911
    Lost territory Sweetwater lost to Carbon, and lost along western boundary to Uinta and former part of Uinta (now Lincoln) when boundaries were adjusted to run on federal land survey lines.
    to Carbonto Uintato Lincoln
    · Wyo. Laws 1911, 11th leg., ch. 77, secs. 12-13/pp. 111-113
  15. 1951
    Boundary clarified Sweetwater boundaries clarified to reflect a resurvey of townships on the southwestern corner of Sweetwater (no change).
    no change
    · Wyo. Laws 1951, 31st leg., ch. 61, sec. 1/pp. 81-82

Land and parcels

What the maps cover in Sweetwater

Who publishes each layer, how good it is, and when we last checked.

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

Sweetwater by the Census

Population
42,272 2020 Census count
Housing units
19,145 2020 Census count
Land area
10,427 square miles
Water area
64 square miles
People per sq mi
4 population ÷ land area

Source: US Census Bureau, 2020 Census; US Census Bureau, 2020 Gazetteer Files. Not endorsed or certified by the Census Bureau.

Rules and offices

Sweetwater County's official site

We have found the county's site but not its offices yet; start there.

County government

See your own lot on these maps

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Questions

Common questions about Sweetwater County

When was Sweetwater County founded?
Sweetwater County was founded in 1867, formed from Laramie County, and named after Sweetwater River.
What is the county seat of Sweetwater County?
The county seat of Sweetwater County is Green River.
Is there an online parcel map for Sweetwater County?
Yes. Wyoming Department of Revenue, Property Tax Division (statewide parcels from county assessors) publishes a parcel map of 27,394 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
Has Sweetwater County's boundary or name changed?
Sweetwater County was created in 1867 from Laramie County. Since then the Atlas of Historical County Boundaries records 12 later changes, chiefly involving Carbon County, Fremont County and Johnson County. It was formerly called Carter.
Is my lot in a flood zone?
We do not have flood maps for Sweetwater County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.

Nearby

Counties next door