The United States acquired the last of the territory that would make up the contiguous United States during which decade?
The United States acquired the last of the territory that would make up the contiguous United States during 1850s. The United States acquired the Southwestern land known as the Gadsden Purchase in 1854 during Franklin Pierce's presidency. This was six years after the Mexican-American War. The last state of the Contiguous United States, commonly called the lower 48, was admitted in 1912 and the fiftieth and most recent state was admitted in 1959.