The Oscar winner recently talked about his four-part movie series: The first chapter opens next week.
It's an epic story, a sweeping saga and a lot to take on.
"I like the situations they were dealing with that were horrifying and sudden, and I like the humanity of it, and that it could exist," Costner said. "We're not too different than the people going west, and they went west for hope. But they went into a land that was hostile, even in its nature, and people who had been there for thousands of years."
Costner very much enjoys Westerns.
"I like seeing how people would arbitrate their problems if there was no law around. You see how people behave when they realize they can just take something if they're strong enough or mean enough," he said. "It feels ugly and wrong, and it's going to require somebody who's not violent to stand up to it."
Costner said the challenge is always to entertain.
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"This isn't just a piece of refrigerator art that my mom will put on the fridge. People are coming on their vacations to the theater to go in and get transported," he said.
The film features a sweeping landscape. It was shot in Utah.
"It's maybe a good reminder that these places still exist; maybe, we should protect them," Costner said. "That's the spirit of environmentalism to me, something that moves me, that my children 50 years from now can be moved by. It's worth protecting."
"The Untouchables" is a Costner favorite, and he loved shooting in Chicago.
"Chicago is always a good place to come; I've never seen a big city feel more like a neighborhood," Costner said. "Your ball team plays in a neighborhood, not in the city, in a neighborhood. And summers, walking at night, there's nothing like it."
When studios wouldn't back the movie project, Costner used his own money to make the films.
He not only stars in them, but wrote and is directing and producing them.
"Horizon: An American Saga" part one opens June 28. The second movie comes out in August.