Under the National Historic Preservation Act of 1966, federal agencies must consider how their projects might affect historic properties such as buildings and archaeological sites, and archaeological and historical investigations along the WIS 57 corridor were carried out under the Section 106 process of identifying resources, evaluating affected resources, determining significance, avoiding harm through redesign when possible, and mitigating significant sites that could not be avoided. Archaeological investigations on WIS 57 began in 1992 and continued through 2008, identifying 107 archaeological sites, testing 78, finding 38 significant, avoiding 30 by rerouting the highway, and mitigating eight that could not be avoided. The identification phase included records review and field reconnaissance to locate previously recorded and unreported historic and prehistoric sites in the study area. The evaluation phase used hand and machine-aided excavations to assess sites likely to be disturbed, and sites considered potentially eligible for the National Register of Historic Places were treated as significant. When significant sites or buildings could not be preserved, data recovery through carefully recorded, large-scale controlled excavation was used to lessen the effects of disturbance, usually by sampling rather than completely excavating a site. Archaeologists also monitored construction in culturally sensitive areas during the project to help prevent incidental disturbance of human remains through close cooperation among WisDOT, contractors, and archaeologists.