Very few people live over 200 miles from a city in the lower-48 states of the US.

To give you an idea: It's 413 miles between Colorado Springs and Wichita[1], leaving a very narrow area to be over 200 miles from either. Grand Island, Nebraska is 402 miles from Denver.

Pretty much all the land is over 200 miles away from a city of at least 50k population is in the great basin. To give you an idea, there are 3 cities in North Dakota (a 200x200 mile rectangle) that have a population of at least 50k, and with Bismarck relatively near the center, that rules out much of the state alone.

1: Dodge City is technically a city, but at much less than 50k population I'll omit it. If you allow anything called a city to count you could probably fit the list of people on a single piece of paper. Using the 50k cutoff you still have 3 cities in North Dakota, a 300x200 mile rectangle.