A group of early Ford enthusiasts pauses to admire the spectacularly eroded formation of “The Teepees” en route through Petrified Forest National Park last month. The 1920s vintage Model A’s and T’s from Michigan, Utah and Nevada were bound for Silver City, N.M., retracing the path of Route 66 and the Old Trails Highway. An early and unpaved precursor to Route 66, the Old Trails Highway section near Holbrook eventually became State Highway 180, running north of its present alignment near the park. Along all of its nearly 2,000 miles from Chicago to the Pacific Ocean, Petrified Forest is the only national park that Route 66 passed directly through.