Little Rock Central High School National Historic Site Boundary Modification Act This bill adjusts the boundary of the Little Rock Central High School National Historic Site in Arkansas to include the 7 residences on South Park Street in Little Rock, which consist of 1.47 acres of specified land. The Department of the Interior may enter into separate cooperative agreements with the owners of such residences to mark, interpret, improve, restore, and provide technical assistance for the preservation and interpretation of their properties. Such an agreement must include a provision specifying that no changes or alterations shall be made to the exterior of the properties except by mutual agreement.