This list should provide great inspiration and bucket list fodder for those planning an upcoming trip.
1. U.S. Route 550 'The Million Dollar Highway', Colorado
Photograph via nealysonwheels
U.S. Route 550 is a spur of U.S. Highway 50 that runs from Bernalillo, New Mexico to Montrose, Colorado in the western United States. The section from Silverton to Ouray is frequently called the Million Dollar Highway. This stretch through the gorge is challenging and potentially hazardous to drive; it is characterized by steep cliffs, narrow lanes, and a lack of guardrails; the ascent of Red Mountain Pass is marked with a number of hairpin curves used to gain elevation, and again, narrow lanes for traffic—many cut directly into the sides of mountains.
2. Highway 1, Big Sur, California
State Route 1 (SR 1) is a major north-south state highway that runs along most of the Pacific coastline of the U.S. state of California. The highway is famous for running along some of the most beautiful coastlines in the USA, leading to its designation as an All-American Road.
Photography by Frans Lanting for NationalGeographic
Highway 1 enters the Big Sur region crossing the San Carpoforo Creek just south of the Monterey County line. For about 90 miles (140 km) from the San Carpoforo Creek to the Carmel River, the road winds and hugs the cliffs of Big Sur, passing various coastal parks in the area. The road also briefly leaves the coast for a few miles and goes through a redwood forest in the Big Sur River valley. This segment of the highway, built between 1919 and 1937, also crosses several historic bridges, including the scenic Bixby Creek Bridge shown above.