Los Alamos County administrative offices are located at 1000 Central Avenue, Los Alamos, NM 87544; phone: 505-663.1750.
At 109 square miles, Los Alamos County is the smallest County in the state. The County has two population centers: Los Alamos, also known as the Townsite, and White Rock. Together, they comprise the political entity as a municipal/ County government. The County is also home to the Los Alamos National Laboratory, or LANL. However, except for certain offices leased to LANL by private owners within the County, LANL properties and functions are predominantly located on federally owned land, outside the jurisdiction of the County. Los Alamos County owns over 6,000 acres, of which 4,000 acres are dedicated to open space.