Between 1870 and 1890, which area had the greatest increase in railroads and, as a result, the most significant economic growth?

Western states and territories

Explanation:

During the second half of the 19th century, the railroad expanded all across America. This led to an increase in movement and trade, greatly benefitting the country and changing the way Americans lived. Although all regions were benefitted, the area that benefitted the most was the West. With the expansion of the railroad, more people were willing to settle in the West. Moreover, more territory became accessible and more goods and services were able to reach the area.

small european communities with shared traditions consolidated into large new states (apex)