Resident Population in Los Alamos County, NM was 19.67500 Thous. of Persons in January of 2024, according to the United States Federal Reserve. Historically, Resident Population in Los Alamos County, NM reached a record high of 19.67500 in January of 2024 and a record low of 15.00000 in January of 1972. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Los Alamos County, NM - last updated from the United States Federal Reserve on April of 2026.