Which counties in Wyoming are losing population?

6 of the 23 counties in Wyoming had fewer residents in 2025 than in 2020. Niobrara County lost the largest share, down 4.5% (−110 people). Sweetwater County lost the most residents (−927).

Of the 6 counties that lost residents between 2020 and 2025, the largest factor was natural change (more deaths than births) in 2 and net domestic migration (more residents moving to other U.S. counties than arriving) in 4 (Census Bureau components of population change).

Data as of 2025 · updated November 5, 2026

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All 6 Wyoming counties that lost residents

Counties losing population in Wyoming
Rank	County	Change 2020–25	Residents lost 2020–25	Residents 2025	Largest factor 2020–25
1	Niobrara County	−4.5%	−110	2,341	Domestic migration (−90)
2	Carbon County	−3.4%	−495	14,013	Domestic migration (−492)
3	Sweetwater County	−2.2%	−927	41,267	Domestic migration (−1,404)
4	Washakie County	−0.8%	−62	7,597	Natural change (−193)
5	Hot Springs County	−0.5%	−21	4,600	Natural change (−279)
6	Teton County	−0.2%	−48	23,333	Domestic migration (−1,267)

How this is ranked

Counties whose Census Bureau resident population estimate for July 1, 2025 is lower than for July 1, 2020, steepest percentage decline first. The largest factor is the most negative of natural change (births minus deaths), net domestic migration and net international migration over the same years (Census Bureau components of population change). Counties with fewer than 1,000 residents, or without a figure for the same period as the others, are left out, as on every ranking.

Source: U.S. Census Bureau, Population Estimates Program (Vintage 2025). Figures come from public federal statistics and are informational only, not investment advice. Check the source before relying on a number. Methodology: how ranks and figures are built. More on every layer: data sources and licences.

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Questions

Which county in Wyoming is losing population fastest?

Niobrara County: down 4.5% between 2020 and 2025, to 2,341 residents (−110 people; Census Bureau population estimates). Next: Carbon County (−3.4%) and Sweetwater County (−2.2%).

How many counties in Wyoming are losing population?

6 of the 23 counties in Wyoming had fewer residents in 2025 than in 2020; the other 17 grew or held steady.

Why are counties in Wyoming losing population?

More county rankings for Wyoming

Counties losing population in other states

Across the U.S.