Much of the early highway, like all the other early highways, was gravel or graded dirt. Due to the efforts of the U.S. Highway 66 Association, US 66 became the first highway to be completely paved in 1938. Several places were dangerous: more than one part of the highway was nicknamed "Bloody 66" and gradually work was done to realign these segments to remove dangerous curves. However, one section through the Black Mountains outside Oatman, Arizona, was fraught with hairpin turns and was the steepest along the entire route, so much so that some early travelers, too frightened at the prospect of driving such a potentially dangerous road, hired locals to navigate the winding grade. The section remained as US 66 until 1953 and is still open to traffic today as the Oatman Highway. Despite such hazards in some areas, US 66 continued to be a popular route.