Founded in 1949, Los Alamos County is one of 33 counties in the state of New Mexico. Historically, Los Alamos County was formed from parts of Sandoval County and Santa Fe County. The city of Los Alamos is the county seat. With FIPS code of 28, Los Alamos County has a population of 19,330 and area of 109 square miles (282 km2).
List of all cities in Los Alamos County, NM alphabetically
| City/Town | Postal Code | Area Code |
| Bandelier National Monument, NM | 87544 | 505 |
| Los Alamos, NM | 87544 | 505 |
| 87545 | 505 | |
| Scientific Lab, NM | 87545 | 505 |
| White Rock, NM | 87544 | 505 |