Los Alamos, County of

Los Alamos County sits in the east Jemez mountains and is named for the community of Los Alamos, its county seat, which in turn was named an Hispanic settlement located here as early as 1880. The name Los Álamos, “the cottonwoods,” likely dates from then.

Los Alamos is the smallest of the state’s counties (108 square miles) and was created out of parts of Sandoval and Santa Fe counties. The locality was selected by the U.S. Government in 1942 as the site to develop the atomic bomb, and under strict security, the laboratory and the community grew rapidly together.

Today, the town combines functions of both city and county to serve the population of just over 185,000. The Los Alamos National Laboratory continues to dominate this community on the Pajarito Plateau.







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