For the same reason you would choose any other destination – with one exception: Legends.
Here, you can visit Custer's home at Fort Abraham Lincoln, from where the 7th Cavalry left for the Little Bighorn. You can visit the grave of Sitting Bull, Custer's opponent at the famous battle.
You can retrace the footsteps of Lewis and Clark and visit their reconstructed Fort Mandan. It was here where they met Sakakawea, who would help guide the expedition to the Pacific. Theodore Roosevelt made the Badlands home.
"Don't just read about legends; experience the legends in North Dakota."