County · code 35028
Los Alamos CountyNew Mexico
Los Alamos County is a county in New Mexico, with its seat in Los Alamos. It was created on March 16, 1949, from parts of Sandoval and Santa Fe counties.
- Founded1949
- County seatLos Alamos
- Named forLos Alamos, New Mexico
- Land area109 sq mi
- Population19,419 2020 Census
- Parcels mapped8,621 checked 14 October 2026
Where it is
Los Alamos on the map of New Mexico
New Mexico has 33 counties and county equivalents, each with its own records office. Shapes with a page are links.
History
Formed in 1949 from Sandoval County and Santa Fe. County
An old deed may name a county that no longer exists, or a boundary that has since moved.
Los Alamos County was formed in 1949 from Sandoval County and Santa Fe. County, and named after Los Alamos, New Mexico. Los Alamos is the county seat.
Deeds and plats from before 1949 for land now in Los Alamos County may have been recorded in Sandoval County and Santa Fe. County.
- 1949Los Alamos County created Los Alamos created from Sandoval and Santa Fe. · N.M. Laws 1949, 19th reg. sess., ch. 134/pp. 319-321
Land and parcels
What the maps cover in Los Alamos
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 8,621 parcels from Los Alamos 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 Los Alamos County yet.
-
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
Los Alamos 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.
Zoning and code
County government
- County government
The official website of Los Alamos County.
See your own lot on these maps
Open Los Alamos 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 Los Alamos County
- When was Los Alamos County founded?
- Los Alamos County was founded in 1949, formed from Sandoval County and Santa Fe. County, and named after Los Alamos, New Mexico.
- What is the county seat of Los Alamos County?
- The county seat of Los Alamos County is Los Alamos.
- Is there an online parcel map for Los Alamos County?
- Yes. Los Alamos County publishes a parcel map of 8,621 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
- Has Los Alamos County's boundary or name changed?
- Los Alamos County was created in 1949 from Sandoval County and Santa Fe. County. The Atlas of Historical County Boundaries records no boundary change since.
- Who issues building permits in Los Alamos County?
- The county's page on building permits: Apply for a permit. Inside a city or town, ask that city first.
- Is my lot in a flood zone?
- We do not have flood maps for Los Alamos County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.
Nearby