The correct answer to this open question is the following.
Unfortunately, you forgot to include the map. Without the map, only you know about the content of it, not us.
However, trying to help you we did some deep research and can comment on the following
There is a map that shows settlement in the 1800s. It also shows roads, trails, and railroads of the same time period. By constructing roads and railroads, people changed their environment. According to the map, this most likely had the following effect: "higher population throughout the western territories."
The Pacific Railroad Act of 1862 called for two companies to build the line from two different directions. We ate talking about the Transcontinental Railroad. The Pacific Railroad Act of 1862 designated the Central Pacific Company and the Union Pacific to build the railroads that connected the East part of the country with the Pacific West. The construction lasted seven years and connected Sacramento, California with Omaha Nebraska. The works were done on May 10, 1869, when both railroads connected in Promontory, Utah.