According to Post 40's Centennial Celebration web page: "Toward the end of 1941, 35 World War I veterans working in the Defense Plant Corporation applied for and were granted an American Legion charter. The new post was designated as 'Basic Magnesium Post Number 40' and would be composed mostly of BMI employees. Only one month after organization, the post membership stood at 101 members, both a remarkable and patriotic feat.

"In 1941, the Basic Magnesium Inc., complex was built for the federal government to produce magnesium and other materials critical to the allied war effort during World War II. Las Vegas was a tiny railroad watering station in 1941, and the Basic Magnesium site was chosen for its proximity to Lake Mead for water, the Hoover Dam for power, and Gabbs for its deposits of magnetite. The Basic Magnesium complex grew rapidly and soon there was a magnesium production facility that would encompass a massive complex, approximately two miles in length. Additionally, there would be a settlement that would provide housing for the workmen and their families, called Basic Town Site. Shortly after our formation in 1941-42, the organizers and charter members of Basic Magnesium Post 40 became very involved in community activities. In addition to the personal sacrifice these men made for the war effort, they also found time to sponsor and organize dinners, dances, a Legion Baseball team, and arrange speakers for meetings on patriotism and the war effort.

"By the summer of 1944, the post had secured the regional finals for our area, thus beginning our long-running and continuous support of American Legion Baseball. In the latter part of 1944, the allies need for magnesium dwindled; the plant stopped production and was shut down. Though thousands of people left the region, enough remained to save the settlement. "In 1953, behind the efforts of some civic-minded settlers, Basic Town Site and the neighboring town of Pittman incorporated as the City of Henderson, named in honor of former Nevada senator Charles B. Henderson."