Luckily, the men had brought Sacagawea along. This mountainous area was the homeland of her people, the Shoshoni, from whom she had been taken five years earlier. Lewis, who needed horses to get his expedition over the mountains, was finally able to contact the elusive Shoshoni, who had never seen a white man before. When Sacagawea came along the trail with her baby son on her back, she suddenly recognized the chief of the Shoshoni, the man for whom she was supposed to interpret - and he was her brother! If this had been the script of a Hollywood movie, the audience would reject the scene as being too far-fetched to be believed, yet it really happened. This happy accident certainly helped Lewis and Clark as they bargained with the Shoshoni for the horses they needed. In their journals, they wrote about the happy reunion of Sacagawea with her long-lost brother. Although she got to see old friends and her family, Sacagawea did not decide to stay with the Shoshoni. She continued with Lewis and Clark, her husband and baby, as the captains looked westward and hoped to find a way to the Pacific Ocean before the harsh winter weather set in.

The explorers traveled overland on horseback, north to Lolo Pass, where they crossed the Bitterroot Range on the Lolo Trail; this was the most difficult part of the journey. The men almost starved on the trail, and were lucky to stumble into the camps of the Nez Perce Indians. The Nez Perce, who had never seen white men before, could easily have killed the starved and weakened explorers and taken their guns and trade goods. These things would have made the Nez Perce rich and powerful. Instead, they treated the explorers with kindness, feeding and helping them, pointing the way to the Pacific. Lewis and Clark left their horses for safekeeping with the honest Nez Perce, and finished making dugout canoes. Finally, they put their canoes in the water for the trip down the rivers to the coast. They floated down the Clearwater, Snake, and Columbia rivers, portaging dangerous waterfalls and trading with friendly Indians along the way. They reached the Pacific Ocean by mid-November 1805. They had fulfilled the goals set for them by President Jefferson. Now they had to make it through another winter and return with their information to the United States.

Once in sight of the ocean, the expedition was lashed by harsh winds and cold rain as they huddled together on the north side of the Columbia River. A decision had to be made about where to stay for the winter. They could not return to the mountains because the snows would be too deep. Finally, Capt. Lewis called for a vote. Everyone in the party got to vote, including York and Sacagawea. Most African Americans and women could not vote in the United States in 1805, but The Corps of Discovery had become a truly democratic organization. The decision about where to spend the winter would affect them all. It was decided to stay on the south side of the river, inland where the winds and rain would be less harsh and their would be more elk to hunt for food and clothing.

In December the explorers built Fort Clatsop on the south side of the Columbia River (near present-day Astoria, Oregon), and settled in for the winter. Lewis and Clark accomplished considerable scientific work, and gathered and recorded information regarding the country and its inhabitants. A detail of men was assigned to make salt by boiling sea water on the Pacific coast. The winter on the Pacific coast was not a cold one, but the weather was dreary, with rain almost every day for months on end and several types of biting insects, like fleas. One day, the Indians reported that a dead whale had washed up on the shore, and Clark led a group of the men who were curious about seeing the whale to the ocean. Sacagawea begged Clark to take her along too, saying that she hadn't traveled so far to miss out on seeing the ocean and the whale. Clark brought her along on the little adventure. The men spent most of the winter making clothing and moccasins out of elk hides, and trying to hunt for food in an area which seemed to have very little game. No contact was made with any trading ships, and Lewis and Clark knew that all the men would have to return to the United States by an overland route.

On March 23, 1806 the return trip began. After a tough journey up the Columbia River against strong currents and many waterfalls, the party retrieved their horses from their friends the Nez Perce, and waited in the Indian villages for the deep mountain snows to melt. It wasn't until June that they could get over the mountains and back to the Missouri River basin. After crossing the Bitterroots Lewis and Clark decided to split their party at Lolo Pass in order to add to the knowledge they could gather. They wanted to be certain that there was not an easier way to cross the continent to the Pacific, and that they had not missed an important potential route or pass. Confident of their survival, Lewis went north along the Missouri River while Clark went south along the Yellowstone River. They planned to rendezvous where the Yellowstone and Missouri Rivers come together in western North Dakota. Clark took the larger group with him, including Sacagawea, her husband and son, and York. Lewis took along the best hunters and outdoorsmen, including George Drouillard and the Field brothers.

While on the Marias River in Montana Lewis' small group had a fight with a party of Blackfeet Indians, and was forced to kill two of them who tried to steal their guns and horses. This was the only violent incident of the entire journey. While out hunting one day, Lewis was accidentally shot by Cruzatte, a nearsighted member of his own crew. The painful wound in Lewis' backside kept him from being able to sit down or continue his journal writing. Soon after this near-disaster, the Corps of Discovery was reunited in North Dakota. They returned to the Mandan villages where they left Charbonneau, Sacagawea and the baby behind. Clark promised to take care of the baby, who he nicknamed "Pomp." Three years later, Charbonneau and Sacagawea brought Pomp down to St. Louis, where William Clark saw to his schooling.

At the Mandan villages Lewis and Clark convinced a chief named Sheheke (they called him "Big White") to come with them to meet President Jefferson in Washington. As they continued down the Missouri River, they had Chief Sheheke, his wife, and an interpreter named Rene Jusseaume with his family along in their dugout canoes. One of Lewis and Clark's men stayed behind. His name was John Colter, and he asked special permission to remain in the Mandan country to trap furs and try to make a living as a "mountain man." Colter later became one of the most famous mountain men, and was the first non-Indian to see the Grand Tetons and what is now Yellowstone National Park.

The Lewis and Clark Expedition returned to St. Louis on September 23, 1806. Nearly all the people of the little town lined the riverbank to welcome them back. Dinner parties and dances were held in their honor. When people in the settled portions of the United States heard that Lewis and Clark had returned from the West, they could barely believe it. Most people had given them up for dead. If wild animals, hunger, harsh weather or Indians hadn't killed them, perhaps they had gotten lost, they thought. Of course, none of those things happened. Lewis, Clark, and nearly all their men returned to St. Louis as heroes. The Corps of Discovery broke up in St. Louis. Lewis and Clark made their way to Washington, where they told President Jefferson in person about the wonders they had seen in the West. The dream of Jefferson and of Jefferson's father had finally come true, and Americans had climbed the Rocky Mountains and walked on the beaches of Oregon.

What did Lewis and Clark accomplish, and what was the significance of their Expedition? From the standpoint of international politics, the expedition altered the struggle for the control of North America, particularity in the Pacific Northwest, by strengthening the U.S. claim to the areas which today includes the states of Oregon, Idaho and Washington. Lewis and Clark also achieved an impressive record of peaceful cooperation with the Indians. The expedition generated American interest in the fur trade. This had a far reaching effect, since it led to further exploration and commercial exploitation of the West. It can be said that Lewis and Clark's trek set off a century of rapid settlement which peopled the West with Euro-Americans and unfortunately disrupted or ruined the cultures and lifestyles of countless Native Americans. Lewis and Clark added to geographical knowledge by determining the true course of the Upper Missouri and its major tributaries. They forever destroyed the dream of a Northwest Passage (a water route across the continent), but proved the success of overland travel to the Pacific. In addition, William Clark produced maps of tremendous value to later explorers. The expedition compiled the first general survey of life and material culture of the village Indians of the Missouri, the Rocky Mountain tribes, and the Native Americans of the Northwest coast.

Lewis and Clark made significant additions to the zoological and botanical knowledge of the continent, providing the first scientific descriptions of many new species including the grizzly bear, prairie dog, pronghorn antelope, and mountain goat. They made the first attempt at a systematic record of the meteorology (weather) of the West, and less successfully attempted to determine the latitude and longitude of significant geographical points.

Lewis and Clark traveled over 8,000 miles in less than 2½ years, losing only one member of their party, at a total cost to the taxpayer of $40,000. By any measure of scientific exploration, the Lewis and Clark expedition was phenomenally successful in terms of accomplishing its stated goals, expanding human knowledge, and spurring further curiosity and wonder about the vast American West. But in the end, it was Thomas Jefferson who was most pleased. In late 1806, Meriwether Lewis returned to Washington, D.C., and spread maps out on the floor of the White House, delighting the President with the tales of his travels. Jefferson's dream, and the dream of his father, Peter Jefferson, had finally come true. The West had been investigated, the Pacific had been reached by an overland route, and America would never be the same again.