Indiana Dunes National Park is a unit of the National Park System designated as a U.S. National Park located in northwest Indiana and managed by the National Park Service. It was authorized by Congress in 1966 as the Indiana Dunes National Lakeshore, the name by which it was known until 2019. The national park runs for nearly 25 miles along the southern shore of Lake Michigan, in Chesterton, Indiana, and contains approximately 15,000 acres.
The National Park has acquired about 95% of the property within the authorized boundaries. Its holdings are non-contiguous and include the 2,182-acre Indiana Dunes State Park (1925), which is owned and managed by the state of Indiana.
The park is physically divided into 15 disconnected pieces. Along the lakefront, the eastern area is roughly the lake shore south to U.S. 12 or U.S. 20 between Michigan City, Indiana, on the east and the ArcelorMittal steel plant on the west. A small extension, south of the steel mill continues west along Salt Creek to Indiana 249. The western area is roughly the shoreline south to U.S. 12 between the Burns Ditch west to Broadway in downtown Gary, Indiana. In addition, there are several outlying areas, including; Pinhook Bog, in LaPorte County to the east. The Heron Rookery in Porter County, the center of the park, and the Calumet Prairie State Nature Preserve and the Hobart Prairie Grove, both in Lake County, the western end of the park. Also within the National Park is the Hoosier Prairie State Nature Preserve, managed by the Indiana Department of Natural Resources.