The day is being observed on Thursday at Charleston Light on Sullivan's Island. The grounds, old Coast Guard quarters, and the boathouse near the unique triangular-shaped light also known as the Sullivan's Island Light are open to visitors.
The inside of the light is closed because of safety concerns, including dangers from flaking lead paint.
The light is located in the island's Coast Guard Historic District, which is administered by the National Park Service.
National Lighthouse Day marks the anniversary of the day in 1789 that Congress passed a law calling for the establishment lighthouses, buoys and public piers in the United States.