Which of the following was a reason why Americans moved west after the Civil War (1860-1900) ?

The completion of the railroads to the West following the Civil War opened up vast areas of the region to settlement and economic development. White settlers from the East poured across the Mississippi to mine, farm, and ranch. African-American settlers also came West from the Deep South, convinced by promoters of all-black Western towns that prosperity could be found there. Chinese railroad workers further added to the diversity of the region's population.

Explanation:

Settlement from the East transformed the Great Plains. The huge herds of American bison that roamed the plains were virtually wiped out, and farmers plowed the natural grasses to plant wheat and other crops. The cattle industry rose in importance as the railroad provided a practical means for getting the cattle to market.