Hamilton was born on July 28, 1894. He spent most of his childhood in Seattle. He was the older of two boys (his brother, Edgar Charles Hamilton, born later) to his parents (Thomas Luther and Henrietta Hamilton). Hamilton's early interests in aviation began when he was around 10 years old. His mother had taken a trip to see the 1904 St. Louis Exposition, where there was a display of gliders organized by Octave Chanute and, somehow on her return, Hamilton became more focused on aeronautics. Mrs. Hamilton may have made a connection with Chanute at the fair since the young Tom Hamilton did not make the long trip with her. Some years later, Hamilton indicated that he often wrote to Chanute concerning technical matters related to his early aircraft, though no record has been found mentioning Hamilton in Chanute's letter collection currently located at the Library of Congress thus far.