From the record
“Catherines Island is a sea island on the coast of the U.S. state of Georgia, 42 miles (68 km) south of Savannah in Liberty County. Catherine's Sound and Sapelo Sound, is ten miles (16 km) long and from one to three miles (4.8 km) wide.”
Wikipedia article St. Catherines Island, CC BY-SA 4.0.
One of 11 National Register listings published here for Liberty County · listed in 1969 · category: District · a National Historic Landmark.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service