An architectural historian identifies all architectural resources in the vicinity of MoDOT projects that are potentially eligible for listing in the National Register of Historic Places (NRHP). The National Historic Preservation Act of 1966 (as amended) was passed in response to concern for historic resources threatened by national economic development. Under this law, the NRHP, State Historic Preservation Offices (SHPO), and the Advisory Council on Historic Preservation (ACHP) were established. Section 106 of this law requires that any federal agency, or agency that accepts federal funds or needs federal licensing, consider the effects of its projects on historic properties. Historic properties are defined as those listed in or eligible for the NRHP under any of four criteria: Criterion A: Buildings that are associated with events that have made a significant contribution to the broad patterns of our history. Criterion B: Buildings that are associated with the lives of famous persons. Criterion C: Buildings that embody the distinctive characteristics of a type, period, or method of construction, or that represent the work of a master, or that possess high artistic values, or that represent a significant and distinguishable entity whose components may lack individual distinction. Criterion D: Properties that have yielded, or are likely to yield, information important to prehistory or history. Early identification of resources is a valuable element in considering project design; it makes it easier to avoid or minimize impact to significant buildings or structures. Cultural Resources reviews are conducted according to the MoDOT Protocol for Cultural Resource Investigations. The first step in identifying and evaluating buildings or structures is to conduct a background check. Information sources for such research include the libraries of the Cultural Resources Section and those of the Historic Preservation Program (HPP) at the Missouri Department of Natural Resources (DNR), previous surveys, the NRHP roster, and topographic and plat maps. Excellent photographs are crucial to this process. For buildings that are older than fifty years, views of each facade are necessary. A building that looks significant from the front may have a large addition at the back, altering its historic integrity. Special considerations include barns, where it is often necessary to have interior photographs of structural details; and general views of older buildings and complexes which show the relationship between buildings. For buildings less than fifty years old, one good photograph, including outbuildings, is usually adequate. All photographs need to be accompanied by and keyed to maps or plans. At this point the information is processed and assembled with a contextual report and project description for submittal to HPP at DNR. HPP requires that Architectural/Historic Inventory Survey Forms be completed for buildings and structures fifty years old or older; the form asks for detailed information about the resource's history and its physical organization. Photographs are included to supplement the form: for example, a photograph might show the foundation material or window configuration. Information obtained from landowners is also helpful, especially for construction dates and occupancy history. Topographic and county maps supplement the information and provide location information. If detailed project maps have been developed, these are also included. Keyed site plans are included if at least one of the architectural resources in a complex is fifty years old or older. The project package is collected with a cover letter, which includes MoDOT staff recommendations to HPP for resource eligibility to the NRHP. HPP has thirty days from receipt of the information for review. If they ask for additional information, then the clock starts over from the day they receive it. If HPP determines that no resources are NRHP-eligible, then the architectural review is essentially complete. If a resource is determined eligible to the NRHP, then the effect of the project on the resource must be determined. There are several types of effect determinations. There may be No Effect if the resource is far enough outside project right of way, or if the project can be redesigned to avoid or minimize impact, or if the project is affecting only a minute portion of a large, complicated system. If there is No Adverse Effect then the architectural historian will prepare the appropriate documentation, which includes a project description, a map showing the area of effects, a summary description of the property subject to effect, and the reasons for considering that the project has no adverse effect. There may be an Adverse Effect if the resource is directly impacted and avoidance is not a feasible and prudent option. If there is an adverse effect on a resource, then the architectural historian will proceed with the preparation of relevant documents, such as the Memorandum of Agreement (MOA) and Section 4(f) Evaluation. The MOA outlines stipulations for mitigating the project's impact to NRHP-eligible properties. Information to accompany this document includes a project description, a description of alternatives that avoid the historic resource, and appendices that typically include maps, photographs, related correspondence, schematic plans showing avoidance alternatives, and estimated costs for the proposed and alternate alignments. A Section 4(f) Evaluation essentially includes the same information, plus the MOA as an appendix. Once the MOA and Section 4(f) Evaluation have been processed, then the architectural historian can proceed with the mitigation stipulations outlined in the MOA. An architectural historian's involvement with a project usually concludes when the mitigation has been accepted by HPP.