Census-designated place and seat of Los Alamos County.
Los Alamos, or the Townsite , is built on four roughly parallel mesas in the east central part of the County. Archaeological and historic evidence of Native American residence in the area dates back to approximately the 10th century. Homesteading in the 19th and 20th centuries was largely for the purpose of summer grazing of livestock. In 1917, Detroit businessman Ashley Pond II started the Los Alamos Ranch School, a boys' school, named after the cottonwood trees that dominated the landscape. In 1942, the Department of War used the power of eminent domain to take over the school and other homesteads in the area to establish a secret location for the Manhattan Project, which designed the first atomic bomb, deployed in World War II.
Much of the housing that remains in place to this day was for the scientists and support staff for the Manhattan Project.