Virginia, 1803. After the United States of America acquires the inmense Louisiana territory from France, a great expedition, led by William Lewis and Meriwether Clark, is sent to survey the new lands and go where no white man has gone before.
| Actor | Role |
|---|---|
 Fred MacMurrayCpt. Meriwether Lewis | Cpt. Meriwether Lewis |
 Charlton HestonLt. William Clark | Lt. William Clark |
 Donna ReedSacajawea | Sacajawea |
 Barbara HaleJulia Hancock | Julia Hancock |
 William DemarestSgt. Gass | Sgt. Gass |
 Alan ReedCharbonneau | Charbonneau |
 Eduardo NoriegaChief Cameahwait | Chief Cameahwait |
 Larry PennellWild Eagle | Wild Eagle |
 Herbert HeyesPresident Thomas Jefferson | President Thomas Jefferson |
 Lester MatthewsMr. Hancock | Mr. Hancock |
 Argentina BrunettiShoshone Woman (uncredited) | Shoshone Woman (uncredited) |
| JJulia MontoyaCrow Woman (uncredited) | Crow Woman (uncredited) |
 Ralph MoodyChief Le Borgne (uncredited) | Chief Le Borgne (uncredited) |
 William PhippsNight Camp Sentry (uncredited) | Night Camp Sentry (uncredited) |
 Walter ReedHelmsman Cruzatte (uncredited) | Helmsman Cruzatte (uncredited) |
 Bill WalkerTom (uncredited) | Tom (uncredited) |
 Helen WallaceMrs. Martha Hancock (uncredited) | Mrs. Martha Hancock (uncredited) |