The Lewis and Clark expedition was dispatched primarily to...

   

• establish an effective claim to the Louisiana Territory, which Jefferson thought to be insecure until Americans explored the region.
• prepare maps and secretly establish forts in preparation for an American invasion of Mexico.
• report on the physical features and the plant and animal life of the Louisiana Territory, in which Jefferson took a great scientific interest.
• identify areas into which the Indian tribes of the Northwest Territory could be forced to move. 

ANSWER: The Lewis and Clark expedition was dispatched primarily to report on the physical features and the plant and animal life of the Louisiana Territory, in which Jefferson took a great scientific interest.