Which statement best identifies a positive effect of westward expansion in the years before the civil war? a) westward expansion led to loss of life and territory for the native americans. b) westward expansion added to the growing conflict between "free" and "slave" states before the civil war. c) westward expansion led to an economic "boom" in the midwest, as new cities and markets were connected by rail and canals. d) westward expansion led to increased numbers of slaves in the west, as southern cotton planters sought new lands to make greater profits. eliminate