The American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Any of several trails, such as the Oregon Trail or the Santa Fe Trail, of westward migration in the United States. The term is sometimes used to refer collectively to all the overland migration routes from the Missouri River to the Pacific Ocean.