Description: This is a statewide polygon feature class of areas in Illinois believed to possess a high archaeologic potential. It was developed by the Illinois State Museum and is intended for coarse regional analysis. The nominal map scale is 1:500,000 with a positional National Map Accuracy Standard value of 832 feet. Note however that the nature of the boundaries themselves, approximate limits of archaeologic potential, make specific statements of positional accuracy unimportant. Background - The Illinois State Agency Historic Preservation Act (P.A. 86-707) mandates state government to preserve, restore, and maintain the historic resources of the state. Activities that can result in change of historic properties undertaken, supported or administered by a State agency are subject to review by the Illinois Historic Preservation Agency (IHPA). The IHPA also regulates private undertakings which require a permit from a State agency. Private undertakings that will affect a documented archaeological site or an area with a high potential for archaeological resources, must inventory and assess the scientific and historic potential of archaeological and historic properties within the project area. The Illinois State Museum (ISM) is responsible for preparing maps illustrating areas with a high probability for archaeological resources. Based on the statewide distribution of documented archaeological resources, a high probability area "means any occurrence of Cahokia Alluvium, Carmi Member of Equality Formation, Grayslake Peat, Parkland Sand, Peyton Colluvium the Batavia Member of the Henry Formation, or the Mackinaw Member, as mapped by Lineback et al. (1979) at a scale of 1:5000,000 within permanent stream floodplains and including: 1) 500 yards of the adjoining bluff line crest of the Fox, Illinois, Kankakee, Kaskaskia, Mississippi, Ohio, Rock, and Wabash Rivers and 300 yards of the adjoining bluff line crest of all other rivers or, 2) a 500 yard wide area along the shore of Lake Michigan abutting the high water mark."