The latest additions are in bold
Ferguson, Allan McAlister, Route 36: Ohio to Colorado - America's Heartland Highway, WFPublishing, 2019. (Ferguson describes a trip along U.S. 36, from Ohio to Colorado, through the small towns and the big cites (Indianapolis and Denver) of this route through America's Heartland.)
Guinn, Jeff, The Vagabonds: The Story of Henry Ford and Thomas Edison's Ten-Year Road Trip, Simon and Schuster, 2019. (Beginning in 1914, Ford, Edison, and other famous people went on annual road trips until 1925. The trips were highly publicized at the time, and the participants famous then and now, but as Guinn puts it, "their adventures as the Vagabonds helped usher in a new national lifestyle, and that should be remembered, too.")
Rutkow, Eric, The Longest Line on the Map: The United States, the Pan-American Highway, and the Quest to Link the Americas, Scribner/An Imprint of Simon&Schuster, Inc, 2019. (From the book jacket: The story of the "the epic quest to link North and South America, a dramatic story of commerce, technology, politics, and the divergent fates of the Americas in the nineteenth and twentieth centuries.")