Fort Union National Monument was congressionally authorized by Public Law 83-429 on June 28, 1954, "to preserve and protect, in the public interest, the historic Old Fort Union, situated in the county of Mora, State of New Mexico, and to provide adequate public access thereto...." The monument was formally established by the NPS] on April 5, 1956. Additionally, under Public Law 100-35, the 100th United States Congress authorized the Santa Fe National Historic Trail on May 8, 1987 to commemorate the over 1,100 mile-long Santa Fe Trail from Old Franklin, Missouri to Santa Fe, New Mexico.