St. Marys stands on the north bank of the St. Marys River, which is the Georgia and Florida line here, in the far southeast corner of the state. The town was founded in 1787 and incorporated in 1802, and its historic district, listed on the National Register in 1976, still runs from the waterfront back to Oak Grove Cemetery. Orange Hall, a Greek Revival house at 311 Osborne Street, was listed separately in 1973.
St. Marys is also the doorway to Cumberland Island. The National Park Service keeps its mainland visitor center at 113 St. Marys Street and the ferry leaves from beside it. The boat is the only way across, and that is much of why Cumberland has stayed undeveloped. Closer in, Crooked River State Park lies ten miles north on GA Spur 40, five hundred acres of maritime forest and salt marsh, with trails, camping and boating.
Back in town, the St. Marys Waterfront Park and the Submarine Museum sit in the same few blocks, and that museum points straight at the local industry. Naval Submarine Base Kings Bay is next door, and the county’s 2025 table reports 7,418 employees at the base and 1,672 at the Trident Refit Facility, against 1,210 at the county school system, 500 at Southeast Georgia Health System and 450 at Lockheed Martin.
The town has been growing on the back of it. The Census counted 18,256 residents and 7,787 housing units in 2020, and the estimate for July 2025 was 20,546, thirteen percent above the count. Camden County School District serves the city and runs St. Marys Middle School at 205 Martha Drive. I-95 Exit 3 brings you in on GA 40 and down Osborne Street, the same exit is the turn for Kingsland two miles inland on US 17, and Jacksonville International is the nearest major airport.
Sourced: founding 1787 and incorporation 1802, Camden County joint land use study, with the National Register nomination distinguishing the 1788 layout and the 1792 authorization. Population and housing units, U.S. Census Bureau 2020 count and Vintage 2025 estimate. Register listings and dates, Camden County’s official inventory. Visitor center address and ferry access, National Park Service. State park, Georgia DNR. Employers, Camden County’s 2025 principal-employer table, which reports countywide rather than city-limit employment.