E. R. Thomas Motor Company was a manufacturer of motorized bicycles, motorized tricycles, motorcycles, and automobiles in Buffalo, New York between 1900 and 1919.
In 1896, Edwin Ross Thomas (1850 – 1936) of Buffalo, New York began selling gasoline engine kits for propelling ordinary bicycles. After forming the Thomas Motor Company, he began selling complete motor-assisted bicycles under the name Thomas Auto-Bi. The Auto-Bi is generally considered to be the first production motorized bicycle made in the United States. By 1903, the company was the largest manufacturer of single-cylinder, air-cooled engines. The Thomas Auto-Bi was later joined by the Auto-Tri, a three-wheeled motorcycle, and the Auto-Two Tri, a motorcycle that could hold three riders.
In 1905, the Thomas Auto-Bi established a new record for a transcontinental crossing of the United States in 48 days. By 1912, the demand for motorcycles had dropped significantly, and the Thomas Motor company discontinued all production of two-wheeled machines.