{"nrhp_refnum":"01001312","name":"Route 66, Litchfield to Mount Olive","other_names":[],"category":"structure","location":{"address":"US 66, N of IL 16 in Litchfield to Mount Olive","address_restricted":false,"city":"Litchfield","county":"Montgomery County","state":"IL","lat":39.16349280000006,"lon":-89.67447907855394,"geom_source":"nps_gis"},"listed_date":"2001-11-29","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Transportation","Engineering"],"significance_levels":["state"],"summary":{"what_it_is":"A 9.35-mile segment of former U.S. Route 66, built as a four-lane divided concrete highway between Litchfield in Montgomery County and Mount Olive in Macoupin County, Illinois. The southbound lanes date to 1943 and the northbound lanes to 1954-1955.","why_significant":"The segment is tied to Route 66 as a major national transportation route, and it served as a strategic defense road during World War II. It is also a representative example of limited-access, federal-aided four-lane highway engineering of the 1940s and 1950s. It retains its original 24-foot cross-section, concrete pavement and 30-foot median.","narrative":"This 9.35-mile stretch of former U.S. Route 66 runs from just north of Litchfield to northwest of Mount Olive, crossing flat farmland in Montgomery and Macoupin counties. It was built as a divided four-lane highway in two stages. The southbound lanes opened in 1943, when wartime convoys and heavy trucks had badly damaged the older road. The northbound lanes followed in 1954-1955. Each roadway is 24 feet wide and made of 10-inch concrete on a crushed-stone subbase, with a 30-foot grass median between them. The design followed limited-access standards of the period and bypassed local towns to reduce traffic tie-ups. Roadside businesses in Litchfield moved or expanded to reach the new traffic. Today the southbound lanes carry two-way traffic under a macadam overlay, while the closed northbound lanes keep their original concrete. The segment is recognized for its link to Route 66 and for its representative mid-century highway engineering, and it keeps its original cross-section and rural setting.","period_of_significance":"Transportation 1943-1956; Engineering 1943-1955","architect_builder":null,"architectural_style":"Other: Limited Access Four-Lane Highway","criteria":["A","C"],"status_note":"State-owned and maintained by the Illinois Department of Transportation. The southbound lanes carry two-way traffic under a macadam overlay, and most northbound lanes are closed to traffic but still visible.","vacant_flag":null,"machine_generated":true,"model":"claude-sonnet-5-5","prompt_version":"v1.0-2026-10-29","generated_at":"2026-10-29 02:55:37.582221-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/opastorage/live/83/8913/28891383/content/electronic-records/rg-079/NPS_IL/01001312.pdf"},"photo":null,"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/28891383","wikipedia":null,"wikidata":null},"indexable":true,"url":"https://nationalhistoricalregister.com/illinois/montgomery-county/route-66-litchfield-to-mount-olive-01001312/"}