In July or August 1952, after dropping my dad off at summer camp, my grandparents decided to take a road trip out west from Pittsburgh. Either they didn't take any pictures between Pittsburgh and Mt Rushmore, or the photos don't exist any more, but in any case, here's their 1952 Rockies Road Trip.
From Pittsburgh, they would have driven west to Chicago and then probably up to Wisconsin and then west through Minnesota and South Dakota. Remember, the Federal Aid Highway Act of 1956 that established the Interstate Highway System wasn't around yet, and so you'd have to take highways with stoplights that passed through all sorts of small towns at the time.
Here's the likely map, or as close as I could make it given that these pathways are significantly improved as interstates now, and with a best guess as to the path based on what locations are in the photos. Instead of Yellowstone to Sequoia via Salt Lake City and Las Vegas, for example, they could have traversed Idaho and Nevada and gone through Reno, Sacramento, and Fresno.
