Roadtrip from Nashville to Yellowstone on a budget with kids

My husband has decided that we need to go to Yellowstone this year for vacation. We have three children ages 11, 9 and 2. We will be on a budget and love corny, unusual places to see and things to do that cost little to nothing. Unusual places to stay too. (Although we have a pug that MAY go along with us). I have mapped out our trip to include a stop in St. Louis, Omaha and Sioux City. We plan to visit the Badlands, Blackhills, Mt. Rushmore, Yellowstone and whatever else we can find along the way.

I guess my question is what are some budget friendly sites and places to stay and what type of money are we talking about for a trip like this.

When you say "corny", the first thing that comes to mind is Wall Drug. There are even a few reasonably priced hotels in town.

GLC, come on, the first thing you think of when you think Corny is Wall Drug?

While I agree that it is corny, they'll be driving right by the Corn Palace to get there! What's more corny than a monument/gymnasium dedicated to honoring Corn?

Going back to the original question, How long do you plan to take to get there and when you say you're going to stop in StL, Omaha, and Sioux City are you talking about overnights? St. Louis to Omaha is a pretty moderate day on the road, but Omaha to Sioux City is less than a 2 hour drive.

Actually, now that I'm thinking corn, another possible stop would be in Sioux City, Iowa. The Jiffy Time Popcorn plant is located in town, and I think they do tours, although you'll want to double check that.