{"nrhp_refnum":"98000979","name":"Illinois Route 4-North of Auburn","other_names":["Sbi 4","State Aid 6"],"category":"structure","location":{"address":"Curran and Snell Rd.","address_restricted":false,"city":"Auburn","county":"Sangamon County","state":"IL","lat":39.61663261950005,"lon":-89.7498952689674,"geom_source":"nps_gis"},"listed_date":"1998-08-06","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Engineering"],"significance_levels":["local"],"summary":{"what_it_is":"Two road segments on the early alignment of Illinois Route 4 (State Bond Issue 4, later U.S. Route 66) north of Auburn, Sangamon County, Illinois: a 1,277-foot concrete stretch finished by 1921 and a 1.53-mile brick road built in 1932, with two 1920 concrete bridges over Panther Creek.","why_significant":"The segments are argued to be good, locally significant examples of early 1920s through 1932 road construction, meeting Criterion C for engineering. The concrete stretch represents the earliest 1926-1930 Route 66 alignment in Illinois, and the brick road reflects a method of road building used in the early twentieth century. Both retain their original width, cross-section, materials and rural setting.","narrative":"North of Auburn, in Sangamon County, Illinois, two surviving pieces of an early highway preserve how the road between Chicago and St. Louis was once built. One is a 1,277-foot stretch of 16-foot-wide Portland cement pavement, completed by 1921 as part of State Bond Issue 4 and later carried the first Route 66 alignment from 1926 to 1930. After a 1932 realignment bypassed it, the pavement stayed largely unchanged, and its curve is now abandoned. The other is a 1.53-mile road that was widened to 20 feet and surfaced with brick in 1932, known today as the Auburn Brick Road. Two single-span reinforced concrete bridges built in 1920 carry the road over Panther Creek. The route was listed for its engineering significance, as representative of Illinois road-building standards between 1920 and 1932. Its rural setting, lane widths, grading and bridges remain much as they were during that period, and both segments are still open to traffic.","period_of_significance":"1920 - 1932","architect_builder":"Unknown","architectural_style":"Other: Concrete Road; Brick Road","criteria":["C"],"status_note":"Both segments are still in use as public roads, though in varying degrees of disrepair; the 677-foot concrete curve is abandoned and has no road designation.","vacant_flag":null,"machine_generated":true,"model":"claude-sonnet-5-5","prompt_version":"v1.0-2026-10-29","generated_at":"2026-10-29 02:55:37.597634-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/opastorage/live/76/8940/28894076/content/electronic-records/rg-079/NPS_IL/98000979.pdf"},"photo":null,"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/28894076","wikipedia":null,"wikidata":"https://www.wikidata.org/wiki/Q113681776"},"indexable":true,"url":"https://nationalhistoricalregister.com/illinois/sangamon-county/illinois-route-4-north-of-auburn-98000979/"}