sentences:  In 1947, a year after the continuation of racing, major improvements at the speedway were made including lighting for night racing, a pedestrian tunnel at the entrance to turn one and the "famous" bridge across the backstretch.In 1949, the American Championship Car Racing National Championship would make an appearance, drawing a large crowd in a race won by Johnny Mantz.At the end of the 1940s the National Roadster Championships were held at the speedway, which would help greatly influence the future of racing in the next decade.