Ontario and San Antonio Heights Railroad Company is a former railway company which operated in Ontario, California. The company's service is noted for using a unique Gravity Mule Car from 1887 to 1895. The mule-car served Ontario until 1895, when the line was electrified by new owners, Ontario Electric Company. It was occasionally used afterwards, when the electric generator in the powerhouse was flooded. The Ontario Electric Company was merged into the Pacific Light & Power Corporation in 1908, and the extension to Pomona commenced work in 1909, which opened New Year's Day 1911. The railroad would go on to be acquired by the Pacific Electric on April 13, 1912. (en)