Which statement best identifies a negative consequence of westward expansion in the years before the civil war? a) westward expansion led to an economic "boom" in the midwest, as new cities and markets were connected by rail and canals. b) westward expansion led to spain's declaration of war against the united states in 1898, which was one of america's costliest wars. c) westward expansion resulted in increased freedom and economic opportunities for african-americans who were fleeing slavery in the south. d) westward expansion led to loss of life and territory for native americans and added to the growing conflict between "free" and "slave" states before the civil war.