The Corps of Discovery has been criticized throughout history. Supposedly, Lewis and Clark did not discover anything, merely learned from the Natives. Others disapprove of Lewis misleading Natives concerning America's intentions, and how established fur trade and settlements caused the near-extinction of many species and deforestation. However, the expedition was more significant than believed, and while America later betrayed the Natives, that was not the intention of Jefferson and the Corps.
The overhunting of animals and swift deforestation in the West were the results of economic growth and while Lewis's deceptions caused Native resettlement, his actions were justified. By securing Native lands, the government-controlled fur trade, and tribes had military protection until the actions of President Andrew Jackson 20 years later, the Trail of Tears.
The journey's impact manifests in the rapid acceleration of colonization in the West. The U.S population grew 36% between 1800 and 1810. The expansion of America was successful due to the Corps of Discovery; mapping the new land for America and producing scientific findings.
"What is not due to those who penetrate the gloom of unexplored regions, to expel the mist of ignorance which envelop science, and overshadow their country."
~Western World Newspaper, October 11, 1806