We take photos (watching as the scuttling clouds change the light cast on the stone faces), skip the huge gift shop in favor of the small bookstore, and wonder what it would be like to attend a Fourth of July celebration here. (No dogs allowed here either, but visitors may leave them in cars in the covered garage. A small grass exercise area is available.)

Mount Rushmore is supposed to be the final special destination this trip, but as I look at the map, I notice that the northeast entrance to Badlands National Park is a mere three miles south of I-90. Isn't this one of the places my parents used to talk of camping when they were grad students at Purdue? A phone call confirms it (see the inset photo on the opening page of this story), and I pull out The Boy's National Parks Passport book to get one final stamp for this road trip (provided he wakes up and actually hikes one of the short trails--that's the rule!).

After several hours exploring the Badlands Loop Road, leaving I-90 at Exit 110 and getting back on at Exit 131, we decide this is a place that deserves its own road trip. Certainly not the ideal camping spot for everyone, the Badlands comprise 244,000 acres of prairie and stark geological formations so bizarre in places you might be on an alien world. I keep imagining what it would have been like to be a pioneer family stumbling on what surely appeared as, literally, a mysterious God-forsaken wasteland.

Dogs are allowed, with restrictions similar to those at Yellowstone, and ranger-led programs promise plenty to keep The Boy busy in a few years. How wonderful to end a great road trip by stumbling on the idea for another one. As Carmen pulls back onto I-90, I hit "Home" on the GPS. Just 1,800 miles to go.

Sidebar: Dog Kennels Near the Parks

Greater Yellowstone/Grand Tetons Area

Happy Tails Pet Resort (Jackson, Wyoming)

Cody Country Bed & Biscuit (Cody, Wyoming)

Yellowstone Cottonwood Dog Kennels (Gardiner, Montana)

Absaroka Pet Ranch (Livingston, Montana)

Greater Mount Rushmore Area

All Seasons Pet Care (Rapid City, South Dakota)

Safe Haven Pet Resort (Rapid City, South Dakota)