Question

Why were railroad companies in a hurry to complete many miles of track-laying in the mid-1800s?

Answer 1

They were given many acres of government - owned land for every mile created.

Answer 2

There were a few main reasons why railroads wanted to expand in the mid-1800s.  One of the main reasons was trading goods back and forth.  Also, another reason was for settlement.  Many towns throughout the United States began to originate near the train stations in town.  

This is how people began to travel back and forth, especially to bigger cities.  When the Transcontinental Railroad was completed in 1869 in Promontory, Utah, it was really a great achievement to have the railroad go across the country to give people the opportunity and businesses to use it for trade, business purposes, and travel.  

Later on, it also started to become a competition between the railroad companies for prices, rates, and who owned which tracks (collisions were common in the late 1800s).