Fred MacMurray

Cpt. Meriwether Lewis

Charlton Heston

Lt. William Clark

Donna Reed

Sacajawea

Barbara Hale

Julia Hancock

William Demarest

Sgt. Gass

Alan Reed

Charbonneau

Eduardo Noriega

Chief Cameahwait

Larry Pennell

Wild Eagle

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)