- Environmental impact: The expedition had a significant impact on the environment, as the explorers often hunted and gathered food from the land, disrupting the natural balance of ecosystems.
- Disease: The expedition was plagued by disease, including smallpox, which they spread to Native American tribes, resulting in widespread devastation and loss of life.
- Cultural clashes: The explorers encountered various Native American tribes with different customs and beliefs, leading to misunderstandings and conflicts.
- Conflicts with Native Americans: The expedition sometimes resorted to violence against Native Americans, particularly when threatened or in cases of perceived theft.
- Loss of life: Several members of the expedition died during the journey, including Sergeant Charles Floyd, who succumbed to illness early on.
- Physical hardships: The expedition endured extreme physical hardships, such as harsh weather conditions, rugged terrain, and limited food supplies, testing the endurance of the participants.
- Failure to reach the Pacific: Although they reached the Pacific coast, Lewis and Clark were unable to establish a permanent settlement there, as they lacked the necessary resources and support.
- Lack of scientific discoveries: While the expedition did gather some scientific information, it fell short of Jefferson's expectations for major scientific breakthroughs.
These negative aspects highlight the challenges and difficulties faced by the Lewis and Clark Expedition, reflecting the complexities and uncertainties of exploration in the early 19th century.