Step 1 : Introduction to the question "6. A lot of brand new U.S. geography was about to be learned after this duo returned to St. Louis, Missouri on September 23, 1806. Who were they?"
...1. Marquette and Joliet 2. Lewis and Clark 3. Casson and La Salle 4. Padilla and Coronado Meriweather Lewis and William Clark set off to survey much of the area from St. Louis to the Pacific Northwest for the U.S. government over a year before, August 31, 1803.