I found this on this site hope it helps
When Napoleon needed money, he sold Jefferson the Louisiana
Purchase, which he had acquired when he conquered Spain. To find out what he'd
just purchased, Jefferson sent Merriweather Lewis and William Clark to explore
it. It covered an area from Louisiana northward to Missouri and across the
biggest part of the Great Plains and Northwest. The team which went with them
included such diverse people as Sacajawea, a Shoshone Indian and her baby Lewis's
slave, French trappers, woodsmen, and other interpreters. Lewis concentrated on
cataloging what they found, such as the various Native American tribes,
animals, and plants, and mapping the region, while Clark was the woodsman who
led the expedition. They went through many hardships, though miraculously only
one member of the expedition died over the several years they were gone. At one
point they were starving in the Rocky Mountains--there was not enough fat on
the deer they shot to keep them alive. They found an Indian tribe to barter
with, but the chief refused to deal with them until Sacajawea walked in--she
was his sister, who had been kidnapped from the tribe at the age of 5! Needless
to say, they got their food. They made it to the Pacific Ocean, where they then
split into two groups, one of which took a more southerly route back.