In 1945, the Santa Fe Railway constructed a new rail bridge over the Colorado River in Needles and Topock, upstream from the Old Trails and Red Rock Bridges. At the same time, California and Arizona had been looking to replace the Old Trails Bridge, as the structure had become insufficiently narrow and too weak for post-war truck and car traffic. Highway engineers determined the retired Red Rock Bridge could serve as a more than adequate replacement. The Red Rock Bridge had previously been rebuilt and reinforced twice during the early 20th century to handle heavier and faster train traffic.