1. The Lincoln Highway
Before the Interstate System became a reality in the 1950s under President Dwight D. Eisenhower, the Lincoln Highway, which ran from New York City to San Francisco, was the most famous overland cross-country route in the US. But even it featured huge patches of unpaved road that turned dusty in dry weather and hopelessly muddy in rain. Case in point: in 1919, when Eisenhower traveled with the US Army’s Cross-Country Motor Transport Train parading a newfangled invention called the "tank" to the American public, it took 62 days to make it from the Atlantic to the Pacific -- and that was with a head start in Washington, DC!
2. The National Old Trails Road (US 40)
Before he was Vice President and eventually President, Harry Truman headed the National Old Trails Road Association, which advocated for a straight-shot US highway system built on the imprint of famous paths of the past (like the Santa Fe Trail). After Truman became a US Senator in 1935, he even bragged about his love of driving to Washington, DC, from his home in Missouri on US 40. But the National Old Trails Road, which started in Baltimore before traversing Pennsylvania, Ohio, Indianapolis, Illinois, Missouri, Kansas, Colorado, New Mexico, Arizona, and Southern California, never earned the same cachet promised by Route 66 -- in fact, the western part of the National Old Trails Road from Las Vegas to Los Angeles was co-opted and certified as 66 as early as 1926. Today, Truman is probably spinning in his grave since to road-trip purists Route 66 is far more mythologized than the mostly forgotten ol’ US 40.