Past the Interstate 40 interchange and a settlement called Essex, Route 66 joins with the National Trails Highway, a coast-to-coast road (known also as the Ocean-to-Ocean Highway) built in 1912 from Baltimore and New York City to several destination points in California. Route 66 joins this highway for the ride west.
Near Essex, you can detour to a place where the temperature is always around 65 degrees Fahrenheit – quite a feat in these parts. You can find it at Mitchell Caverns, a series of limestone caves with stalactites, stalagmites, flowstone, and other limestone formations of interesting shapes and sizes.
Cavern tours, lasting an hour-plus are available to the public, except for mid-June to mid-September. The caverns are part of the Mitchell Caverns Natural Preserve run by the State of California.