In 1915, the US Army started testing trucks that were made to go off-road. They wanted to know if trucks could replace horses. Trucks could carry bigger loads and were easier to take care of. A truck can run as long as it has fuel, and a good truck should not break. A horse has to be fed and rested, and can get sick. Tests showed that trucks worked better than horses. The Army started replacing all horses and mules with trucks. One of the testers, Lieutenant Dwight D. Eisenhower, later became the President of the United States and started the Interstate Highway System.