Westward movement; westward expansion of the United States
Historical term referring to the 19th-century expansion of U.S. territory westward across North America.
I learned about the Westward movement in American history class.
Refers to the ideological belief in manifest destiny that drove the Westward movement, while 西漸運動 is the historical movement itself.
Compound of 西漸 (せいぜん, 'gradual westward advance') and 運動 (うんどう, 'movement'). The term is a direct translation of the English 'Westward movement'.