The site was first preserved as a national cemetery by the Secretary of War on January 29, 1879, to protect graves of the 7th Cavalry troopers buried there. Proclaimed National Cemetery of Custer's Battlefield Reservation to include burials of other campaigns and wars on December 7, 1886. The name has been shortened to "Custer National Cemetery," and although it had been the site of Custer's grave, he was reinterred to West Point Cemetery in 1877.
Reno-Benteen Battlefield was added on April 14, 1926. Transferred from the War Department to the National Park Service on July 1, 1940. Redesignated Custer Battlefield National Monument on March 22, 1946. Listed on the National Register of Historic Places on October 15, 1966. The site was renamed Little Bighorn Battlefield National Monument by a law signed by President George H. W. Bush on December 10, 1991.
The first memorial on the site was assembled by Captain George Sanderson and the 11th Infantry. They buried soldiers' bodies where they were found and removed animal bones. In his official report dated April 7, 1879, Sanderson wrote:
"I accordingly built a mound out of cord wood filled in the center with all the horse bones I could find on the field. In the center of the mound I dug a grave and interred all the human bones that could be found, in all, parts of four or five different bodies. This grave was then built up with wood for four feet above ground. The mound is ten feet square and about eleven feet high; is built on the highest point immediately in rear of where Gen’l Custer’s body was found..."
Lieutenant Charles F. Roe and the 2nd Cavalry built the granite memorial in July 1881 that stands today on the top of Last Stand Hill. They also reinterred soldiers' remains near the new memorial, but left stakes in the ground to mark where they had fallen. In 1890 these stakes were replaced with marble markers.
The bill that changed the name of the national monument also called for an "Indian Memorial" to be built near Last Stand Hill. It is fairly common at national battle sites in the United States for combatants on both sides of the conflict to be honored.
Markers honoring the Indians who fought at Little Big Horn, including Crazy Horse, have been added to those of the U.S. troops. On Memorial Day, 1999, the first of five red granite markers denoting where warriors fell during the battle were placed on the battlefield for Cheyenne warriors Lame White Man and Noisy Walking.
The warriors' red speckled granite memorial markers dot the ravines and hillsides just as do the white marble markers representing where soldiers fell. Since then, markers have been added for the Sans Arc Lakota warrior Long Road and the Minniconjou Lakota Dog's Back Bone.
On June 25, 2003, an unknown Lakota warrior marker was placed on Wooden Leg Hill, east of Last Stand Hill to honor a warrior who was killed during the battle as witnessed by the Northern Cheyenne warrior Wooden Leg.