Henry Gannett (August 24, 1846 – November 5, 1914) was an American geographer who is described as the "father of mapmaking in America.

[2] He was a founding member and president of the National Geographic Society, a founder of the American Association of Geographers, and a co-founder and president of the Twenty Year Club or Twenty Year Topographers which was formed at the U.S.G.S.

[3] He was the son of Hannah Trufant (née Church) and Michael Farley Gannett.

[3][4] In 1871 he declined a position as an astronomer with Charles Francis Hall's ill-fated Polaris Expedition to the North Pole.

Previously individual mapmakers and agencies had to compete for money from Congress for project funds.

On July 1, 1882, John Wesley Powell appointed Gannett as the chief geographer in charge of the topographic mapping division of the USGS, a position he held until 1896.

[5][4] Around 1884, he persuaded various organizations doing the surveys, including the railroads, to begin using similar datums so the data could interconnect.

As the chief geographer, he oversaw work on the topographical atlas of the United States.

[2][4][7] In 1909 he was named chairman of a special committee to examine and verify the records of Robert E. Peary in the controversy with Frederick Cook over who was the first to reach the North Pole.

[7][2] He was also Chair of the Society's Research Committee, organizing expeditions to Alaska, La Soufriere, Mount Pelee, Peru, and the Polar Seas.

[3] He was also a member of the Washington Academy of Sciences, the Royal Geographical Society of London, the Royal Scottish Geographical Society, and the Philadelphia Geographic Society..[12][2][13][9][14][3][10][4] Gannett was a co-founder and president of the Twenty Year Club or Twenty Year Topographers which was formed at the United States Geological Survey Topographic Division in the winter of 1910–1911.

[3] They had a son, Farley Gannett who was an engineer for the Water Supply Commission of Pennsylvania.

[4] Gannett died at his home in 1840 Biltmore Street, Washington, D.C. on November 5, 1914, after being ill for about a year with Bright's Disease.

[14] The day of his funeral, the National Geographic Society closed its offices and draped the building in mourning.