The Union automobile was a vehicle manufactured by the Union Automobile Company from 1902 until 1905. It was designed by John William Lambert, who had developed the three-wheel Buckeye gasoline buggy in 1891. Over the next decade, Lambert substantially refined the vehicle, with modifications including an additional wheel, a more powerful engine, and a new transmission system. The Union Automobile Company was formed as a subsidiary of Lambert's Buckeye Manufacturing Company solely to manufacture the Union, which took its name from Union City, Indiana, the city where it was built and which endorsed its production. In total, the company built over three hundred Union automobiles, before development shifted to the Lambert automobile, the Union's successor.