County facts · Population growth · October 24, 2026

Fastest Growing Counties in New Mexico, 2020 to 2025

New Mexico's fastest growing counties by percent and by people added, April 2020 to July 2025 Census estimates, with each official parcel map.

Looking for the fastest growing counties in New Mexico? From the Census Bureau's April 1, 2020 estimates base to its July 1, 2025 estimate, New Mexico went from about 2,117,492 to 2,125,498 residents, a change of +8,006 (+0.4%). The fastest growing county by percentage was Valencia County (+7.4%), while Sandoval County added the most people (+10,732, +7.2%).

Each table links the county's Platbookmapper page and its official parcel viewer, so you can go from the growth numbers straight to the property lines.

New Mexico growth at a glance

• Counties: 33
• Statewide, April 2020 to July 2025: +8,006 residents (+0.4%); July 2024 to July 2025 alone: −1,276 (−0.1%)
• Grew: 10 of 33 · Lost residents: 23
• Fastest growing by percent: Valencia County (+7.4%); most people added: Sandoval County (+10,732)
• Counties with more deaths than births over the period: 26 of 33

The 10 fastest growing New Mexico counties by percent

These 10 added about 32,409 people combined. The median county changed by −1.5%.

The 10 counties that added the most people

The top 10 account for about 100% of all the gains in the counties that grew.

Where the new residents came from

The Census Bureau splits each change into natural change (births minus deaths), net domestic migration (moves from other parts of the US) and net international migration. Totals for April 2020 to July 2025 in the five fastest growing counties:

In all 5, moves from elsewhere in the US were the biggest source of growth. The three parts do not add up exactly to the total because the Census Bureau also carries a small residual.

The last year alone: July 2024 to July 2025

1. Valencia County: +1.4% (+1,119)
2. Sandoval County: +1.2% (+1,954)
3. Eddy County: +1.1% (+710)
4. Torrance County: +1.0% (+158)
5. Doña Ana County: +0.4% (+987)

5 of these 5 are also in the 2020–2025 top 10, so the growth is not a one-year blip.

Counties losing residents

23 of New Mexico's 33 counties had fewer residents in July 2025 than in April 2020. The steepest declines:

• McKinley County: −6.5% (−4,762, now about 68,119)
• Hidalgo County: −5.9% (−247, now about 3,929)
• Union County: −5.8% (−238, now about 3,844)
• Harding County: −5.7% (−37, now about 617)
• Socorro County: −4.6% (−759, now about 15,838)

What fast growth means on a parcel map

• New lots show up as plats first. When land is subdivided, the plat is recorded with the county and the parcel layer catches up on its own schedule, so a brand-new lot may not appear on the map for a while. Check the recorder's recent plats if a parcel looks missing.
• Parcel numbers change after splits. A tract that was one parcel last year can be several today. Search by owner name or address as well as by an old parcel number.
• City limits move. Growing cities annex land, which changes who handles zoning and permits even though the county still keeps the deed and the tax map.
• Percent is not the same as people. A small county can post a big percentage on a modest number of new residents, so read the people-added column too.

Related guides

• Largest counties in New Mexico
• New Mexico county GIS websites by viewer
• New Mexico landowner maps for hunting
• Fastest growing counties in the US
• US counties losing population

More: All New Mexico counties on Platbookmapper

Sources

• U.S. Census Bureau, Population Estimates Program, county totals, Vintage 2025 (April 1, 2020 estimates base and July 1, 2020–2025 estimates, with components of change). Percent change is from the April 1, 2020 estimates base to the July 1, 2025 estimate.
• Platbookmapper county GIS directory (live data file behind our county pages, pulled October 24, 2026) for each official parcel viewer.