Answer:
To learn more about the geography and to find a waterway for America from Mississippi to the Pacific Ocean.
Step-by-step explanation:
The Lewis and Clark Expeditions were expeditions that began in 1804 after the Louisiana Purchase. Until that moment, Americans did not know the territory they bought, because of that it was needed to explore.
The expedition lasted two years and at the end of it, they were able to have a geographic, ecological and social report about the new territory.