When During what time period did many western states enter the union how many western states entered during this time?

Many western states entered the Union during the late 19th and early 20th centuries, particularly between the 1860s and 1912. During this time, a total of 13 states joined the Union, including notable additions like Colorado, Wyoming, and Arizona. This period was characterized by westward expansion and the fulfillment of the Manifest Destiny ideology.