Which was the last major land acquisition the united states mad prior to the beginning of the civil war? a) mexican cession b) gadsden purchase c) adams-onis treaty d) louisiana purchase

B. The Gadsden Purchase was the last major land acquisition prior to the Civil War. In 1853, the ten million dollar purchase made by U.S. ambassador James Gadsden completed the continental U.S. as we know it. Initially, the strip of land was viewed as necessary for the completion of a southern trancontinental railroad. Eventually, the Southern Pacific Railroad was constructed here.