Fort Union National Monument is located in northeastern New Mexico and preserves the remains of a significant military outpost established in 1851. The fort played a crucial role in protecting trade routes and facilitating westward expansion during the 19th century. It served as a supply depot for the U.S. Army and was instrumental in the conflicts with Native American tribes. Today, visitors can explore the site, which includes reconstructed buildings and interpretive trails. The monument offers insights into the history of the American West, the role of the U.S. Army, and the interactions between settlers and Native American tribes.