The biggest change the Lewis and Clark Expedition caused was opening up the west, and by making a map of the territory. It impacted the Westward Expansion most by traveling to the new territory gained from the Louisiana Purchase, by mapping out the land out west. with this new information, they triggered the beginning of several inventions that make traveling west easier.
People now had knowledge of the land. The country began losing people to this new land out west.
The Lewis and Clark Expedition affected Westward Expansion by traveling to the new territory. This was new land that we had no clue about it; we had no idea if it was safe there, or if there was anything important there. "The object of your mission is to explore the Missouri River, and such principle stream of it, by it's course and communication with the water of thePacific Ocean may purpose offer the most direct and practicable water communication across the continent, for the purpose of commerce." ("Message on the Lewis and Clark Expedition, 1803." DISCovering U.S. History, Gale, 2003. Research in Context,go.galegroup.com/ps/i.dop=MSIC&sw=w&u=pioneer&v=2.1&id=GALE%7CEJ2104210103&it=r&asid=e0d6382e4a878c06c6a94f4ddf58303e. Accessed 28 Apr. 2017.) It also says a similar thing in another passage, stating, "For president Thomas Jefferson, the Louisiana Purchase was a great triumph. In one transaction doubled the size of the United States, adding 600 million acres to it's territory at a cost of less than 3 cents an acre" ("The Louisiana Purchase." Gale Encyclopedia of U.S. History: War, Gale, 2009. Research in Context,go.galegroup.com/ps/i.dop=MSIC&sw=w&u=pioneer&v=2.1&id=GALE%7CEJ3048500030&it=r&asid=7c4122332953e7e17a0f5509dbb0401a. Accessed 28 Apr. 2017.) They both state that there is new land and/or that it should be explored. With the knowledge of this new territory, Lewis and Clark were able to determine if this new area is livable.
The Lewis and Clark Expedition also allowed them to create a map of the area. This map was looked at by people that would make people aware of everything in this new territory. "The expeditions purpose suddenly expanded to include exploration and evaluation of the new lands to determine their settlement and commercial potential" ("The Lewis and Clark Expedition." Gale Encyclopedia of U.S. History: Government and Politics, Gale, 2009. Research in Context, go.galegroup.com/ps/i.dop=MSIC&sw=w&u=pioneer&v=2.1&id=GALE%7CEJ3048400086&it=r&asid=a6fc80710da86bb1fd42684d67cf99e8. Accessed 1 May 2017.)
Lastly, the Lewis and Clark Expedition triggered the beginning of many inventions. Without knowing what is west, inventions would not have been able to make it easier to travel there. Things like the transcontinental railroad would have never been invented. "The completion of the transcontinental railroad was a truly nation-building event and the country, despite hardships and drawbacks, had been made better for it." ("Transcontinental Railroad." Gale Encyclopedia of U.S. History: War, Gale, 2009. Research in Context, go.galegroup.com/ps/i.dop=MSIC&sw=w&u=pioneer&v=2.1&id=GALE%7CEJ3048500097&it=r&asid=08dcedfb587c4d1f341264a968de3be7. Accessed 1 May 2017.)
This change happened around 1803, because we had doubled in size due to the Louisiana Purchase. This affected both the south and north equally. At this time, the idea of manifest destiny was very popular. It saying that America was destined to spread. After exploring this territory, people now had an idea of where to go, and this triggered many inventions that helped make this travel easier. This made more people want to move out west.