{"nrhp_refnum":"76002094","name":"Benjamin Banneker: SW 9 Intermediate Boundary Stone","other_names":["Intermediate Stone of the District of Columbia"],"category":"object","location":{"address":"18th and Van Buren Sts.","address_restricted":false,"city":"Arlington","county":"Arlington County","state":"VA","lat":38.89210570300003,"lon":-77.15916614899999,"geom_source":"nps_gis"},"listed_date":"1976-05-11","is_nhl":true,"nhl_designated_date":"1976-05-11","areas_of_significance":["Community Planning and Development","Agriculture","Engineering","Black","Science","Social History","Invention"],"significance_levels":["national"],"summary":{"what_it_is":"A one-foot-square sandstone intermediate boundary stone, marked SW-9, in Falls Church Park at 18th Street and Van Buren Drive, Arlington, Virginia. It is one of the forty stones placed in 1791-92 to mark the original District of Columbia boundary.","why_significant":"The nomination ties the stone to Benjamin Banneker (1731-1806), a self-taught mathematician, astronomer, almanac writer and surveyor. He served as scientific assistant to Major Andrew Ellicott in surveying the Federal City and its boundary. The form presents him as one of the most famous Black Americans of his era and as evidence of Afro-American contributions to the young nation.","narrative":"A small sandstone marker in Falls Church Park, at 18th Street and Van Buren Drive in Arlington, Virginia, records the original boundary of the District of Columbia. Known as SW-9, it is one of forty intermediate stones set along the ten-mile square in 1791 and 1792. Each was a foot-square block of sandstone inscribed with the jurisdiction, the state name, the year and the magnetic variance. This stone now rises about 15 inches above ground, is sinking, and sits inside a dark green iron fence directly on the line between Arlington County and the City of Falls Church. Its significance comes from Benjamin Banneker, the Maryland-born mathematician, astronomer and almanac author who assisted Major Andrew Ellicott in surveying the new Federal City. Banneker built a wooden striking clock in 1753, published almanacs, and wrote to Thomas Jefferson challenging his views on Black intellect. The stone commemorates his public service to the new nation.","period_of_significance":"1792-present","architect_builder":null,"architectural_style":null,"criteria":[],"status_note":"Stone is about 15 inches above ground, sinking, with a worn top and inscriptions largely unreadable; its bronze plaque is missing and held by the county survey office, and an iron fence surrounds it. The form lists it as altered and unoccupied.","vacant_flag":null,"machine_generated":true,"model":"claude-sonnet-5-5","prompt_version":"v1.0-2026-10-29","generated_at":"2026-10-29 02:51:56.715609-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/opastorage/live/85/6789/41678985/content/electronic-records/rg-079/NPS_VA/76002094_NHL.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/76002094/5fa211a762-800.webp","url_1600":"https://nationalhistoricalregister.com/media/76002094/5fa211a762-1600.webp","licence":"CC BY-SA 3.0","author":"Loop202","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:DC_Boundary_stone_SW9_(Banneker),_21_Oct_2012.JPG\" rel=\"noopener\">Loop202</a>, <a href=\"https://creativecommons.org/licenses/by-sa/3.0\" rel=\"license noopener\">CC BY-SA 3.0</a>, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:DC_Boundary_stone_SW9_(Banneker),_21_Oct_2012.JPG"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/41678985","wikipedia":"https://en.wikipedia.org/wiki/Benjamin_Banneker:_SW-9_Intermediate_Boundary_Stone","wikidata":"https://www.wikidata.org/wiki/Q4888239"},"indexable":true,"url":"https://nationalhistoricalregister.com/virginia/arlington-county/benjamin-banneker-sw-9-intermediate-boundary-stone-76002094/"}