{"nrhp_refnum":"71000355","name":"Twin Lights Historic District-Cape Ann Light Station","other_names":["Thatcher's Island Twin Lights","Cape Anne Light Station"],"category":"district","location":{"address":"1 mi. E of Rockport on Thatcher's Island","address_restricted":false,"city":"Rockport","county":"Essex County","state":"MA","lat":42.637375532500045,"lon":-70.57642414075605,"geom_source":"nps_gis"},"listed_date":"1971-10-07","is_nhl":true,"nhl_designated_date":"2001-01-03","areas_of_significance":["Engineering","Transportation"],"significance_levels":["national","local"],"summary":{"what_it_is":"A district on Thacher's Island, a roughly 50-acre rocky island about one mile off the coast east of Rockport, Massachusetts. It contains two 124-foot granite lighthouse towers built in 1860-61, plus associated late 19th century wooden buildings.","why_significant":"The nomination calls these the last twin lights in existence in the United States. Twin lights were an early way to tell one lighthouse from another, and the rest were dismantled or destroyed once revolving lenses made distinct patterns possible. The island also has a long history, with the first twin lights lit in 1771 and a shipwreck in 1635 that gave the island its name.","narrative":"Thacher's Island, about a mile off Rockport on Cape Ann, carries two circular granite lighthouse towers, each 124 feet tall, built in 1860-61. The battered stone walls have slit windows lighting the interior stairs, two balconies at the top, and a one-story brick entrance building at the base of each tower. A few late 19th century wooden houses stand near the southeast light. The island is named for Anthony Thacher, who survived a 1635 shipwreck that killed his children and others. Massachusetts authorized twin lights in 1771, and the original 45-foot towers were first lit that December. The federal government took them over in 1789, and Congress funded their rebuilding in 1859. The nomination states they are the last twin lights in the United States. The north tower went out of use in 1932, while the southeast tower remains active with an electric light visible for 19 miles. Both towers appear on Rockport's town seal.","period_of_significance":null,"architect_builder":null,"architectural_style":null,"criteria":[],"status_note":"The southeast light is in operation and in excellent condition, maintained by the Coast Guard. The north light, discontinued in 1932, needs weather protection, and the north light and 22 acres were slated for disposal.","vacant_flag":null,"machine_generated":true,"model":"claude-sonnet-5-5","prompt_version":"v1.0-2026-10-29","generated_at":"2026-10-29 02:11:54.398456-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/opastorage/live/18/7902/63790218/content/electronic-records/rg-079/NPS_MA/71000355.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/71000355/68534ebfa0-800.webp","url_1600":"https://nationalhistoricalregister.com/media/71000355/68534ebfa0-1600.webp","licence":"CC BY-SA 3.0","author":"Tim Pierce","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Thacher_Island_twin_lighthouses.jpg\" rel=\"noopener\">Tim Pierce</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:Thacher_Island_twin_lighthouses.jpg"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/63790218","wikipedia":"https://en.wikipedia.org/wiki/Cape_Ann_Light_Station","wikidata":"https://www.wikidata.org/wiki/Q5034568"},"indexable":true,"url":"https://nationalhistoricalregister.com/massachusetts/essex-county/twin-lights-historic-district-cape-ann-light-station-71000355/"}