MoDOT has included cultural resource studies in its project development beginning in the 1960s, and several thousand cultural resources studies have been performed since that time. Most MoDOT projects include a review of known information including previous cultural resource projects and recorded sites on file with the Department of Natural Resources and the Archaeological Survey of Missouri. The review of records is typically followed by an on the ground investigation, or Phase I cultural resource survey, in which the project area is walked and examined for cultural resources, which may include photographing structures. This survey is designed to locate unrecorded cultural resources and verify previously recorded archaeological sites and historic structures. Typically, an archaeological survey consists of examining the ground surface for artifacts. If the ground is obscured by vegetation, or if evidence suggests that sites may be buried by later soil deposition, small shovel test excavations, typically about a foot wide and a foot or two deep, may be dug to look for artifacts and expose the soil profile. These units are always carefully backfilled. Other types of sites may be visible on the surface and include foundations, wells, and occasionally small family cemeteries. In the early stages of project planning, the MoDOT specialists often will examine a wide corridor or several alternative locations to determine which location will have the least impact on the environment while best serving the needs of the public. Once a cultural resource is located, the MoDOT cultural resources staff evaluates this resource. With archaeological sites, this work is designated a Phase II investigation and may include limited excavation and/or historical research to determine if the site is worthy of further study or protection. Not all sites can provide us with information about the past, so this testing allows MoDOT to wisely use its resources in fulfilling its obligations to the preservation laws. If the site is found to be able to provide important research data, additional work, or Phase III mitigation, may be undertaken to minimize the loss of the information contained within the site. This mitigation may take several forms, including avoidance of the site or the in-place preservation of the site through protective burial or restrictions on the types of construction activities permitted on the site. If these two options cannot be applied to protect the site, then an intensive archaeological excavation may be conducted so the information and artifacts are preserved for study. These investigations, the results, and the ultimate curation of the artifacts are reviewed by the Historic Preservation Program of the Department of Natural Resources, who insure that all laws and regulations have been followed. A similar process is followed when important buildings or bridges will be impacted by a MoDOT project. The structure is photographed and documented by architectural or bridge historians and the results are submitted, with MoDOT's recommendations, to the Historic Preservation Program of the Department of Natural Resources for review and comment. If a structure is found to be a significant resource, it may be nominated to the National Register of Historic Places. If such a significant building cannot be preserved in place or moved, it is thoroughly documented with detailed photographs and a written history that are placed on file with the Missouri Historic Preservation Program, and in some cases, the Library of Congress in Washington D.C.