Which innovation had the greatest impact on westward migration immediately after the american civil war? a. telephone b. electricity c. steam-powered boats d. transcontinental railroad?

d.transcontinental railroad

Explanation:

The construction of the first transcontinental railroad began in the United States in 1863 and was completed in May 1869. The idea of building a transcontinental railroad by Asa Whitney at the congress in 1845. The railroad was built by several companies, including Western Pacific Railway Company, Central Pacific Railway Company of California and Union Pacific Railroad Company.