Once upon a time there was a boy named Marty McFly who had to study for a big test about Lewis and Clark.

Marty wanted adventure and wanted to learn more about Lewis and Clark.

So Marty decided to use the time machine that his friend Dr. Emmett Brown made to go back in time.

From Marty's past experiences with time travel he learned not to talk with people because if he did it could change the future. So he just observed.

Marty set the time machine to go to St. Louis on May 14, 1804. Marty knew that he would have to meet Lewis and Clark where the Missouri empties into the Mississippi River.

When Marty arrived he took notes on Lewis and Clark.

 Along the way, Clark oversaw the men and carefully mapped the route. 

 Lewis carefully studied and collected specimens of animals and plants. 

The trip was difficult, the men lived outdoors, hunted for food, and rowed the keelboat (along with two smaller boats) up the river, often carrying the boat from the shore when the current got too heavy or the river became difficult to cross.

During the first season of travel, they met the Missouris, the Omahas, the Yankton Sioux, the Teton Sioux (Lakota), and the Arikaras.

By October, Lewis and Clark had reached what is now North Dakota, but they were nowhere near the Missouri's headwaters and winter was at hand. 

Since little was known about the route beyond the Mandan villages, Lewis and Clark decided to build a fort for winter with the Mandans and their Hidatsa neighbors. 

During the winter, Lewis and Clark hired Toussaint Charbonneau, a French fur trader, and his wife, a Shoshone woman named Sacagawea, realizing that this woman could help them by acting as an interpreter with her people, who lived near the Missouri's headwaters.

In the spring, the captains sent the keelboat back down the river with a few men and many items for Jefferson, including a report of the expedition, samples of soil, minerals, and plants, Indian items, and even some live birds and a prairie dog, which had never been heard of in the East. 

Most of the expedition continued up the river in canoes, taking along Sacagawea, her husband, and their newborn baby, Jean-Baptiste.

The group spent the next months making their way west up the river into land unknown to white men.

When they finally reached the area of the Missouri's headwaters, they sought out the Shoshones. 

 As it turned out, Sacagawea's brother was chief of the village they first met.

With her help, the party obtained the horses they would need to get across the mountains ahead.

As the party began crossing the mountains on horseback, it soon became obvious that the hope of finding a northwest water route was a false one. 

 The expedition had to make its way on the Lolo Trail across the vast Bitterroot Mountains, already covered with snow in September.