Friends and family (who know my wife and I are nearing the end of a decade project to visit the 59 National Parks) have sent me interesting links like this, where some enterprising map nerd (God bless us every one) made a beautiful route on Google Maps, taking you to 47 National Parks in the 48 states (the rest are in Alaska, Hawaii, American Samoa, and US Virgin Islands):
It is interesting from a mathematical theory point of view, but one of the shortcomings is all of the other scenic places they miss along the way. We have seen at least as many National Monuments / Rec. Areas, etc. as National Parks and many of them are just as amazing, and most of the National Parks are surrounded by scenic wilderness, forest, etc. (Also, Pinnacles NM became Pinnacles NP after we visited it. NPs are not created out of nothing so we saw it before it was 'famous'.)
A few nitpicks: the map takes the longer boat trip from Michigan to Isle Royale instead of the shorter one from Grand Portage, MN. Also, there is no concessioner (boat) from Dry Tortugas to western Florida, just back to Key West.
They miss that some of the Parks have multiple districts that require their own driving. The Parks are not 'points' on a map but are really multiple points, like Voyageurs, Everglades, Theodore Roosevelt, Canyonlands, Black Canyon, Yellowstone, and Yosemite. (Yellowstone is bigger than two states, Rhode Island and Delaware, combined.) If the map makers are 'ticking boxes', collecting passport stamps, you would think they would want to get multiple stamps per Park (multiple visitor centers with different stamps).
Also, assuming they are trying to minimize driving and avoiding flying home in the middle of the trip, I take it that they want to spend at most one or two seasons doing this (3-6 months), if not less time. And if we are assuming they want to enjoy the Parks and not just hop out of the car to stamp a Passport, then they are visiting and hiking a lot of desert Parks in the summer (Grand Canyon, Arches, Big Bend, Saguaro in Tucson -- it says it in the name), or if they are not doing it in summer, they are ignoring high altitude winters which are typically October through May at other Parks, such as Rocky Mountain in Colorado and Glacier in Montana.
In other words, the logistics of this are not as simple as points on a map. Armchair travel is not the same as real world travel. More power to you if you make the journey, just be safe and have fun, and try to set realistic expectations. Also, try not spend all of your time driving interstate highways between Parks. And don't miss out on some of the lesser State Parks, National Monuments, and man-made stuff like world-class cities, restaurants, and National Historic Sites too.
As a wise individual once said the point is not to make good time, but to have a good time.