Lighthouse Friends has a page with history on individual lighthouses and appears to be based on good research (includes sources)
National Park Service’s Lighthouse Heritage Site includes an inventory of lighthouses around the U.S. and a few features on lighthouse history
U.S. Coast Guard Historian’s Office - includes a section devoted to lighthouses and an extensive bibliography
U.S. Lighthouse Society (contains Keepers’ Log articles on lighthouses and database based on some National Archives records)
Other miscellaneous websites:
"Built in America" HABS/HAER has documentation of many lighthouses (also search on "light station) Architectural
drawings and / or photographs for the following lighthouses are included in this collection: Cape Hatteras, Grosse Point,
North Point, Pensacola, Point Loma, Point Wilson, Portland Head, Presque Isle, Rock of Ages, Sand Island, Sandy Hook, Ship
Shoal, and Split Rock
Finding aid for lighthouse records in the National Archives created by Candace Clifford
Lighthouse Postcards at the Smithsonian National Museum of American History