Lewis and Clark went to Louisiana to buy land and visit the western expedition.

1803 Louisiana land purchase case aroused American interest and extended to the west coast of the United States. A few weeks after the purchase, American President Thomas Jefferson advocated expanding westward, and the US Congress allocated $2,500 to send 10 or 12 people to explore the western ocean. They study the Indian tribes, plants, geology, topography and wildlife in this area, and evaluate the potential interference of British and French Canadian hunters and trappers as well as those set up in this area. The expedition didn't cross North America. About ten years later, 1793, the alexander mackenzie expedition was the first time that Europeans crossed the Pacific Ocean.

Jefferson chose captain meriwether lewis to lead the expedition, which was later called the expedition. Lewis chose william clark as his partner. Due to the bureaucratic delay of the US Army, Clark officially set out with only the rank of second lieutenant. But Lewis still led the expedition with Clark, and said that Clark was always called "the captain".

1804 On May 14, two commanders led an expedition. At the same time, the Spanish ambassador asked Sassi, governor of new Spain (now Mexico) and commander-in-chief of inland province, to "arrest Captain Luis and his men". Sassi, famous for his ruthlessness, incited Comanches allied with Spain and sent them to assassinate Luis and Clark, but these Indians failed to find the expedition.

At the end of August, the expedition entered the territory of the Indian tribe Laktas and Sioux. These Indian tribes are the rulers of the great plains in the midwest of the United States, and they are known as the "kings of the brave." Jefferson wrote a personal letter to the Lakota people long before the expedition set out, saying that he was afraid of the great power of this country. The expedition had a friendly and calm meeting with the Lakota people, and the hospitable Indians invited the members of the expedition to smoke. Lewis and Clark were surprised when they saw this long pipe. They named the smoking place the pipe cliff.

On September 25th, in today's South Dakota, the expedition met another Laktas tribe. This tribe is notorious for robbing past businessmen. The expedition met Chief Tothonga. During the meeting, the Lakota people wanted to attack the expedition suddenly, but they were moved by the brave actions of the soldiers, and Chief Totonga gave up his initial hostility.

In autumn, the expedition set up Mandan Fort near the Missouri River where Mandan people live, and prepared to spend the winter here. After spring came, they set foot on the journey again on April 7. They passed yellowstone river, a tributary of the Missouri River, and came to the Missouri River Waterfall. After July, they entered the mountain at the entrance of the Rocky Mountains. In August 1805, 1 1, they met the warriors of the Shoshone tribe. In June+10, 5438, the expedition crossed Idaho into Washington state, and crossed the fastest rivers in North America, Snake River and Qingshui River.

101October 16, they arrived at the Columbia River, from where they went to the Pacific Ocean by water. Three days later, the expedition team reached the end of their dream-the Pacific Ocean. The log reads: "At the wide mouth of the Columbia River, we enjoyed the sea view of the Pacific Ocean."

The expedition spent nearly a month investigating the Pacific coast and nearby plains, as well as Indian tribes along the Pacific coast. They built a fort here, called Thorpe Castle in Collert. The completion of this fortress declared that the tentacles of American military power extended to the Pacific coast for the first time. Thorpe Castle in Collert not only became the first American outpost in the Pacific Ocean, but also became a landmark in the western United States, and became the highest achievement of Lewis and Clark's exploration.

1On March 23rd, 806, the expedition set foot on its way home. Perhaps because of the instigation of the British Northwest Fur Company, the friendly Indians became hostile on their way back. Nevertheless, they returned to St. Louis at noon on September 23rd. 1806.