New Mexico sought statehood as early as 1849, but political and other factors delayed acceptance. A constitution was adopted and a state government set up in 1911, and on January 6, 1912, New Mexico was admitted to the Union as the 47th state.

Pancho Villa raided Columbus in 1916, and a punitive expedition under Brigadier General John J. Pershing pursued his band into Mexico.

With the construction of Los Alamos National Laboratory during World War II, New Mexico became a center for nuclear-weapon research and development. The world's first atomic bomb was exploded on July 16, 1945, on the White Sands Proving Grounds near Alamogordo. Industrial expansion, which began shortly after the war, continued in the 1950's as uranium and oil deposits were discovered.

In the 1960's, an alliance of Mexican-Americans agitated for restoration of land under old Spanish land grants. Their claims were not upheld. In 1970, however, the federal government returned to the Taos Indians 48,000 acres (19,000 hectares) of land taken from them early in the century and incorporated into Carson National Forest.

In the 1970's New Mexico became an important supplier of coal, natural gas, oil, and uranium to the rest of the country. The nationwide recession of the early 1980's caused serious economic problems in the state; particularly affected were farming, ranching, and mining. Flooding in 1983–84 produced severe property damage. With increased demand for natural gas and crude oil in the mid-1980's, economic recovery began.

As of the late 20th century, a large component of New Mexico's economy is space and nuclear research, comprised of both military and nonmilitary projects. Although government military spending has recently decreased, tourism, manufacturing, and construction industries have been growing.