Question

The Lewis and Clark expedition (1803–1806) was important because it (1) determined the route of the first transcontinental railroad (2) opened an all-water route to the Gulf of Mexico (3) removed the British threat from the Northwest Territory (4) increased understanding of the area included in the Louisiana Purchase

Answer 1

The Lewis and Clark expedition (1803–1806) was important because it "(4) increased understanding of the area included in the Louisiana Purchase," since the US had recently purchased this new territory.