Key Players: There were several key players in the Lewis and Clark Expedition. Two of the most obvious key players were Meriwether Lewis and William Clark. Meriwether Lewis was Thomas Jefferson's personal secretary, and he was the one that was originally given the task of exploring the West. Lewis was a good man for the job due to his keen sense of observation and attention to detail. Also, Lewis had served six years in the Frontier Army, so he knew how to take care of himself. Lewis invited his old friend, William Clark, to go with him. Clark had also served in the Army (he began his military career at age nineteen) and had skills essential to the mission. Clark's skills included building forts, drawing maps, leading pack trains, and fighting Indians. Even with their own abilities, Lewis and Clark knew they needed help, so they gathered the group that would become known as the Corps of Discovery. A well-known member of the Corps was the Shoshone Indian, Sacajawea. She acted as an interpreter, and Sacajawea made herself generally useful by doing things such as digging for roots, collecting edible plants, and picking berries. In addition to the more popular names of the Corps, other less heard-of people were also important. One of the sergeants (the four sergeants were ranked just below the captains - Lewis and Clark) was a man named Nathaniel Pryor. Usually, only unmarried men were allowed to be on the Expedition, but Pryor was the exception. Despite being a deviation from the rule, Nathaniel Pryor was considered "a man of character and ability". He was often assigned responsibilities as army administration. Another sergeant was Charles Floyd, and he was one of the first to volunteer for service in the Corps. Charles Floyd provided a great record of the expedition's progress through his daily journal (which was later published). Unfortunately, Floyd died on the journey and was the only fatality of the expedition.

Expedition Accomplishments: Although the Lewis and Clark Expedition didn't fulfil its original purpose, it did accomplish many feats. The Expedition had set out to find and explore a waterway that ran all the way to the Pacific Ocean, but they instead came back with the knowledge that one did not exist. This discovery, or lack thereof, was an important accomplishment of the expedition. The Corps of Discovery also accomplished mapping a route to the Pacific, bringing back important information about the West and it peoples, and securing good relations with Western Indians.

Plant and Animal Species Discovered: Many new plant and animal species were discovered by the Lewis and Clark Expedition. Animals such as the eagle, rattlesnake, prairie dog, bobcat, and grizzly bear were discovered. The Expedition also discovered plants like the Lemon Scurfpea, Osage Orange Tree, and Saguaro Cactus.