Frank Manly Thorn was an American lawyer, politician, government official, essayist, journalist, humorist, and inventor. He served as the sixth Superintendent of the United States Coast and Geodetic Survey. The first non-scientist to hold that position, he guided the Coast and Geodetic Survey through a critical period of reform following the exposure of improprieties under his predecessor, and he defended it from being abolished or diminished by its critics.

The United States Coast and Geodetic Survey was the first scientific agency of the United States Government. It existed from 1807 to 1970, and throughout its history was responsible for mapping and charting the coast of the United States, and later the coasts of U.S. territories. In 1871, it gained the additional responsibility of surveying the interior of the United States and geodesy became a more important part of its work, leading to it being renamed the U.S. Coast and Geodetic Survey in 1878.