American imperialism
![Countries around the world with U.S. military bases. Such U.S. bases have generated controversy and opposition by some in foreign countries](/Images/godic/202502/19/American_bases_worldwide.svg3334.png")
![On the cover of Puck published on April 6, 1901, in the wake of gainful victory in the Spanish–American War, Columbia—the National personification of the U.S.—preens herself with an Easter bonnet in the form of a warship bearing the words](/Images/godic/202502/19/Puck_cover23334.jpg")
![This cartoon reflects the America's imperial ambitions following a quick victory in the Spanish–American War of 1898. The American flag flies from the Philippines and Hawaii in the Pacific to Cuba and Puerto Rico in the Caribbean.](/Images/godic/202502/19/Victor_Gillam_A_Thing_Well_Begun_Is_Half_Done_1899_Cornell_CUL_PJM_1136_013334.jpg")
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American imperialism is the economic, military and cultural influence of the United States on other countries. Such influence often goes hand in hand with expansion into foreign territories. The concept of an American Empire was first popularized during the presidency of James K. Polk who led the United States into the Mexican–American War of 1846, and the eventual annexation of California and other western territories via the Treaty of Guadalupe Hidalgo and the Gadsden purchase.