Based on extensive documentary and factual material, the origins, driving forces and ideology of American expansionism are analyzed, the relationship between US domestic and foreign policy in the 19th century. and during the entry of the United States into the era of imperialism. The history of the acquisition by the United States of Louisiana, Alaska, the annexation of Florida, the capture of Texas, Hawaii, aggression against Mexico during the revolution of 1910-1917 is presented. The book criticizes ideological concepts (Monroe Doctrine, Pan-Americanism, open door doctrine in China), Washington's policy in Latin America, Asia, and Oceania is traced.