In April 1851, by an act devised by Lt. Col. Edwin Sumner, army headquaters of the newly conquered New Mexico territory were moved from Santa Fe (a place that was, to quote Sumner a 'sink of vice and extravangance') to the area that is now the Fort Union National Monument. It was a strategic location, close to many Indian tribes and on the Cimarron Branch of the Santa Fe Trail. Fort Union played a large role in helping the United States 'win the west.'
The coming of the railroad in 1879 rendered Fort Union no longer necessary. The fort was built up three times between 1851 and 1869. Today, visitors will have to use their imaginations, the current remains are a mere skeleton of what once stood here. The visitor's center has an excellent selection of books related to westward migration and western history.
Take care when exploring the ruins and grounds, rattlesnake sightings are not unheard of. Stay on the trails to be safe.