What was the u. s. government's role in building america's first transcontinental railroad?

The government helped private companies build the railroad.

Explanation:

The Transcontinental Railroad was a continuous railroad line that was built between 1863 and 1869. The government of the United States played a very significant role in building this railroad. The government provided subsidy bonds as well as company issued mortgage bonds in order to finance it. Moreover, the railroad was built by private companies over public lands provided by extensive US land grants.

these civilizations were located around fertile rivers, where they could produce an abundance of crops