The term US Motor City is referring to the city of DETROIT, which is located in the state of Michigan. DETROIT is known for its automotive industry and is often referred to as the 'Motor City' due to its long history of automobile production. It is home to several major car manufacturers, including Ford, General Motors, and Chrysler. DETROIT has been an important center of the American auto industry since the early 20th century and continues to be a major player in the industry today.