Historical Markers in
Los Alamos County, New Mexico

The state has a rich tradition of cowboy culture and rodeo, with many annual events celebrating this heritage. One of the most famous is the annual Albuquerque International Balloon Fiesta, which features hundreds of hot air balloons and draws thousands of visitors each year.
Los Alamos County is located in the northern part of New Mexico and is known primarily for being the site of the Los Alamos National Laboratory. The history of Los Alamos County dates back thousands of years to the native Pueblo people who inhabited the area. The Pueblo people built settlements and farmed the land until the Spanish arrived in the 16th century. The Spanish established several missions, but these were abandoned by the late 17th century due to conflict with neighboring Native American tribes.

In the late 19th century, the region saw an influx of Anglo settlers and became a popular destination for ranching and mining. In 1917, the Los Alamos Ranch School was established as an educational institution for boys. The school brought prominence to the region and attracted families from across the country.

The turning point in the history of Los Alamos County came in 1942, during World War II, when the U.S. government selected the area to be the site of the top-secret Manhattan Project. The Los Alamos National Laboratory was built to develop the atomic bomb, and thousands of scientists, engineers, and other personnel were brought to the region. The development and testing of the atomic bomb had a profound impact on the community, forever shaping the legacy of Los Alamos County.

After the war, Los Alamos National Laboratory continued to be a major research and development center, attracting scientists from around the world. Today, Los Alamos County is known for its scientific research, high-tech industry, and natural beauty. It remains a tight-knit community with a unique and complex history that is deeply intertwined with the atomic age.

This timeline provides a glimpse into the major events and milestones that have shaped the history of Los Alamos County, New Mexico.

  • 1942 - Los Alamos County is established as part of the Manhattan Project.
  • 1943 - Los Alamos Ranch School is taken over by the US Army to accommodate the Manhattan Project.
  • 1945 - The first atomic bomb, nicknamed "Little Boy," is tested at the Trinity Site near Los Alamos.
  • 1947 - Los Alamos County becomes an official county in the state of New Mexico.
  • 1956 - Los Alamos National Laboratory is officially designated as a government-owned, contractor-operated facility.
  • 1970 - The population of Los Alamos County reaches its peak with over 19,000 residents.
  • 2000 - Cerro Grande Fire devastates Los Alamos, destroying hundreds of homes and over 48,000 acres of land.
  • 2010 - Los Alamos County celebrates its 100th anniversary since its establishment.