Pitt and Norton are joining forces with HBO and National Geographic for the project, which is an adaptation of the STEPHEN AMBROSE book UNDAUNTED COURAGE: MERIWETHER LEWIS, THOMAS JEFFERSON, AND THE OPENING OF THE AMERICAN WEST.
Norton will direct at least one of the episodes, and will join Pitt as one of the project's executive producers.
Norton says, "Lewis and Clark's expedition is as great a story as you could ever hope to tell, and like so many people, Brad and I have both been drawn to it for years.
"We both always agreed that compressing that story in a feature-length film ruined the spirit of it... so we sat down and said, 'How can we really do this justice?'"
The actors plan to be as hands-on as possible during the project's development process, and will be choosing a writer to oversee it.