Which department did the Lighthouse Service fall under?

• A. Department of the Navy
• B. Department of the Interior
• C. Department of Commerce
• D. Treasury Department

Answer: (D)

Lighthouses and other navigational aids have historically been treated as civilian maritime infrastructure that funds and administers safety at sea. The Lighthouse Service was organized under the Department of the Treasury because its mission was about safe navigation and supporting maritime commerce, with funding and administration coming from Treasury’s purview. It remained in Treasury until its functions were folded into the U.S. Coast Guard in 1939, after which organizational structure changed. The Navy focuses on military operations, the Interior oversees lands and natural resources, and Commerce handles trade policy—none of these align with the lighthouse administration as it was historically structured. So the Lighthouse Service fell under the Treasury Department.