At the beginning of the 20th century, the appearance of internal combustion engine provided people with new locomotive driving force. 1925, the first diesel locomotive in American railway history was put into operation. The efficiency and cleanliness of diesel locomotives are much higher than that of heavy-duty steam locomotives, and they are not limited like electric locomotives. The United States, Britain, Canada and other countries realized diesel locomotives within 10 years. Diesel locomotives have become the owners of railways.