The country's expansion beyond North America began in 1856 with the passage of the Guano Islands Act, causing many small and uninhabited, but economically important, islands in the Pacific Ocean and Caribbean Sea to be claimed. Most of these claims were eventually abandoned due to competing claims from other countries or the guano having been mined out. The Pacific expansion culminated in the annexation of Hawaii in 1898, after the overthrow of its government five years previously. Alaska, the last major acquisition in North America, was purchased from Russia in 1867.