On October 6, 1998 the 105^th Congress of the United States authorized the Sand Creek Massacre National Historic Site Study Act. This legislation (Public Law 105-243) was introduced by Senator Ben Nighthorse Campbell and mandated that the National Park Service identify the location and extent of the massacre area and determine it’s suitability and feasibility as a potential National Historic Site. The legislation also required cost estimates for potential acquisition, development, and operations and identified alternatives for administration of the area. Resulting from this legislation was a 366 page Site Location Study and a two volume Special Resource Study and Environmental Assessment. The Location Study identified the length and extent (the boundaries) of the Sand Creek Massacre. The Study used an interdisciplinary approach to its task – oral history, archived sources and other historical documentation, archeology and remote imagery, geomorphology, aerial photography, and traditional tribal methods were used. These efforts resulted in the partnering of the National Park Service, the Colorado Historical Society, property owners, volunteers, and the Cheyenne and Arapaho Tribes in Oklahoma, the Northern Cheyenne Tribe in Montana, and the Northern Arapaho Tribe in Wyoming.

During the Site Location Study, the Sand Creek Massacre Project Team was able to identify several areas along Sand Creek where, based upon the interdisciplinary methods, the Indian camp and much of the activity of November 29 and 30, 1864 likely took place. As a running engagement, the Sand Creek Massacre continued up Sand Creek and across it’s valley into the surrounding hills and prairie. As this research unfolded, a range of opinions developed regarding the exact location of the Sand Creek Massacre. Some debate continues regarding the specific locations of internal features. Potential areas initially considered included the Dawson South Bend and the northern edge of the Dawson Bend; the Bowen Middle and Bowen South Bends; the Rhoades/Bowen Bend; and the Dewitt/Ballentine Bend. These areas, with one exception, stretch across the open country of Township 17 South, Kiowa County into the southern edge of Cheyenne County. The final boundaries, agreed upon by all participants in the study, encompass about 7500 acres in Kiowa County - from the Bowen Middle Bend to south of the Dawson Bend. This area is now on the National Register of Historic Places.

Twenty five months after the Site Study Act, the United States Congress concurred with the site boundaries and authorized the Sand Creek Massacre National Historic Site with Public Law 106-465, November 7, 2000. The Act requires the National Park Service to acquire from willing sellers enough area to adequately protect, interpret, memorialize, and commemorate the site. The legislation also confirms the sites national significance, and provides an opportunity for tribes, the State of Colorado, and other entities to be involved in its support and development. Establishment will provide enhanced cultural understanding and define the conditions of descendant and tribal access for traditional, cultural, or historical observance.

Currently,  through its partnership with The Conservation Fund and with Colorado State Historical Fund assistance, the National Park Service has acquired approximately 920 acres of the proposed 12,500 acre site. An additional 1,465 acres (the former Dawson Ranch) was recently purchased by Southwest Entertainment, Inc. which in turn intends to convey the property to the Cheyenne and Arapaho Tribes. It is anticipated this land may be legislated into tribal trust status, thence managed by the National Park Service. Most land within the authorized boundary remains under private ownership. Within the massacre site boundaries are places of great historic importance– the location of the Cheyenne village and several Arapaho lodges; the point(s) from which the Colorado Regiments first spotted the encampment; the location of Indian pony herds; the area of flight, bordering Sand Creek, that the Indians took during and after the initial attack; the general path of battalion advancements, individual skirmishing and other collateral action; the military bivouac area for the nights of November 29 and 30; spots in the creek and along it’s banks where the Cheyenne dug sandpits/survival pits, and the points from which battery salvoes were launched into the camp and later into the sandpits. All of these areas are on land authorized for inclusion in the National Historic Site.