The Lewis and Clark expedition came about because of The Louisiana Purchase, which was negotiated between Thomas Jefferson and Napolean from France. The Kingdom of France wanted to sell the land to the U.S because of financial pressures resulting from other conflicts with the United Kingdom and other revolts in their territories. Thomas Jefferson was excited about the prospect of acquiring the land and wanted to get control of the Mississippi River port of New Orleans. It was possible for the government to purchase an area of land that stretched from the Mississippi River to the Rocky Mountains for $15 million. The price of $2.50 per square mile was hard for Jefferson to pass over, and he perused the sale.

The purchase was not supported by the Federalist Party, but Jefferson and Secretary of State James Madison convinced Congress to fund the purchase after the debate. The sale would add 828,000 square miles (2,144,510 square km) of land from France. In April 1803, the land was purchased under President Thomas Jefferson’s government. The purchase would result in The Louisiana Purchase, which included areas of the Mississippi River that were mostly unexplored and unknown to both the U.S. and France.

The Louisiana Purchase almost doubled the size of the U.S. It covers many states and provinces in the present-day U.S and Canada. The purchase also includes Arkansas, Missouri, Iowa, Oklahoma, Kansas, and Nebraska. Big areas of North and South Dakota; Montana, Wyoming, Colorado, and some of Minnesota, New Mexico, Texas; New Orleans, Louisiana, Alberta, and Saskatchewan were also discovered during the journey.

Thomas Jefferson and others in the government wanted to know what was purchased as they had little knowledge of the area in question. After the purchase of the land, President Jefferson asked Congress to approve $2,500 for a journey of exploration into the west.

The goal of the journey would be to map the newly acquired Louisiana territory. Another primary objective was to find a water route to the Pacific Ocean through the north-west and increase trade throughout the region and the U.S. Other secondary purposes were to study plant and animal life as well as geography. Establishing relations and dealing with the Indian tribes was another objective. The journey would accomplish a resounding number of goals related to biology, scientific discovery, botany, archeology, and even climatology.

From the beginning of the journey, many of the party took journals of what they saw and experienced on their trip. The journey was important in the history of the U.S and exploration and expansion. It would be of vital importance in the subsequent knowledge of the area and what other explorers could expect on their journey westward. The Lousiana Purchase needed to be justified, and a group of men would be responsible for showing the fruitfulness of such a purchase by Jefferson and the government.