Ithamar Parsons Berthrong (February 26, 1853 - July 29, 1936) was an American surveyor, inventor, and draftsman active with the General Land Office of the U.S. Department of the Interior. Berthrong was born in Rochester, New York. He was made chief of the drafting division on March 23 of 1907. He is associated with many of the most important early 20th century maps issued by the GLO, among them, important maps of Arizona, Colorado, Wyoming, Oregon, Washington, and more.