From Hackberry, US 66 then curved northeast through the mountains, passing through the towns of Valentine and Crozier. Upon entering a small mountain valley, the highway passed through the town of Truxton before entering the mountains again at Peach Springs. Between Valentine and Peach Springs, SR 66 takes a later routing of US 66, which is straighter and has fewer curves. The older, less straight alignment, used through 1940, can be seen on either side of present-day SR 66. A natural feature and tourist attraction called the Grand Canyon Caverns, just east of Peach Springs, are among the largest dry caverns in the United States.