From East to West:
Lake Geneva, Wisconsin, Yerkes Observatory holds the largest refracting telescope in the world.
Milton, Wisconsin, Milton house, a stop on the underground railway to help escaped slaves from The South.
Mount Horeb, Wisconsin, Cave of the Mounds. A series of underground caves.
House on the Rock, a house built on a monolith, utilizing the rock as part of the house.
Prairie du Chein, Villa Louis, Fort Crawford, and Cemetery, the smallest national cemetery. This area dates from and was involved in the Revolutionary War.
Rochester, Minnesota, The Mayo Clinic and museums on the history of medicine.
Mitchell, South Dakota, The Corn Palace. Murals made entirely of corn.
Cactus Flat to Wall, South Dakota, The Badlands. View prickly pear cactus. At Wall, there is Wall Drug an institution in itself.
Rapid City, South Dakota, The Black Hills and Mt Rushmore. Lots to see and do in this area.
Sundance, Wyoming, Devil's Tower, a must see.
Crow Agency, Montana, The Little Bighorn Battlefield.
These are places I have personally visited and can reccommend.
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Whether you think you can or think you can't, you're right.