Fred MacMurray
Cpt. Meriwether Lewis
Charlton Heston
Lt. William Clark
Barbara Hale
Julia Hancock
William Demarest
Sgt. Gass
Eduardo Noriega
Chief Cameahwait
Herbert Heyes
President Thomas Jefferson
Lester Matthews
Mr. Hancock
Argentina Brunetti
Shoshone Woman (uncredited)
Julia Montoya
Crow Woman (uncredited)
Ralph Moody
Chief Le Borgne (uncredited)
William Phipps
Night Camp Sentry (uncredited)
Walter Reed
Helmsman Cruzatte (uncredited)
Bill Walker
Tom (uncredited)
Helen Wallace
Mrs. Martha Hancock (uncredited)