The federal penitentiary located on Alcatraz Island in San Francisco Bay closes. The island had been home to a lighthouse, a military fortification, and a military prison over the years. In 1972, it would become a national recreation area open to tourists, and it would receive national landmark designations in 1976 and 1986.

German-born theoretical physicist Albert Einstein publishes his general theory of relativity. Among the effects of the theory are phenomena such as the curvature of space-time, the bending of rays of light in gravitational fields, faster than light universe expansion, and the warping of space time around a rotating body.

In the U.S., the state of Nevada passes a resolution allowing for legalized gambling. Unregulated gambling had been commonplace in the early Nevada mining towns, but was outlawed in 1909 as part of a nationwide anti-gaming crusade. The leading proponents of re-legalization expected that gambling would be a short term fix until the state's economic base widened to include less cyclical industries. However, gaming proved over time to be one of the least cyclical industries ever conceived.

During World War II, the 99th Pursuit Squadron, aka the Tuskegee Airmen, is activated. The group is the first all-black unit of the Army Air Corp, and serves with distinction in Africa, Italy, Germany and other areas. In March 2007 the surviving airmen and the widows of those who had died received Congressional Gold Medals for their service.