When Lassen Volcanic National Park was established in 1916, its scenic features, expansive views, and volcanic landscapes could be reached only by horseback or on foot. In 1925, through the vision of early National Park Service Director Stephen T. Mather and private citizens like Michael Dittmar and others, construction on a scenic boulevard began in earnest. The timing coincided with the rapid rise of automobile touring after Henry Ford's ten-millionth automobile rolled off the assembly line the year before. As the new road was built, visitation by car rose from 142 in 1924 to 2,200 in 1925. A principal design challenge was balancing automobile access with preservation of the park's pristine condition, and Mather intervened to halt overly ambitious road plans so construction to scenic features would not disturb the park's wilderness integrity. The Volcanic Legacy Scenic Byway and All American Road now extends from Lassen Volcanic National Park in California to Crater Lake National Park in Oregon, creating a volcano-to-volcano drive.