One modern town that was built in the late 1800s to serve the railroads was

Cheyenne, Wyoming, grew as a railroad town after the Union Pacific Railroad reached the area in 1867. It was established to support railroad construction and operations, making Cheyenne the town built to serve the railroads. New York and San Francisco were much older cities, and Omaha was already an established city before the railroad boom.

AI-written and checked against the verified answer.