Any young person could be cast in your ensemble. Remember, there are lots of small featured roles in the vignette songs that are easily filled by the ensemble, instead of double-cast with one of the named characters. Feel free to cast Congressmen, Thomas Jefferson, Lewis, Clark, Sacajawea, the Sun, the Planets, the Comet Team, Reginald, Doctor, Geraldine, Gerald, Franklin, the Team and the Crowd from the ensemble.