Ralph Emerson Twitchell (1859-1925) was an American historicist and mayor of Santa Fe, New Mexico. He was chairman of the Rio Grande Commission, which drafted a treaty between the United States and Mexico leading to the building of the Elephant Butte Dam in New Mexico. Twitchell helped organize the first National Irrigation Congress in 1891. For forty-three years he was a member of the legal department of the Santa Fe Railroad. He was prosecuting attorney for Santa Fe County and special counsel for the U.S. Department of the Interior dealing with Native American and water-rights cases