The Louisiana Purchase encompassed all or part of 15 current U.S. states and two Canadian provinces, including Arkansas, Missouri, Iowa, Oklahoma, Kansas, Nebraska, parts of Minnesota that were west of the Mississippi River, most of North Dakota, nearly all of South Dakota, northeastern New Mexico, Northern Texas, the portions of Montana, Wyoming, and Colorado east of the Continental Divide, and Louisiana west of the Mississippi River, including the city of New Orleans (parts of this area were still claimed by Spain at the time of the Purchase.) In addition, the Louisiana Purchase contained small portions of land that would eventually become part of the Canadian provinces of Alberta and Saskatchewan. The purchase, which doubled the size of the young nation, comprises around 23% of current American territory.

The purchase allowed Jefferson to plan something he had talked about since taking office: an expedition deep into the unmapped and largely unknown continent with the final destination being the Pacific Ocean. This could prove the most significant of the goals that Jefferson - a person who thought of himself as a scientifically-minded thinker - wanted to accomplish as president.

Though he knew he had bought a huge amount of land, Jefferson wasn't entirely sure of what he had bought, so he asked a team led by Meriwether Lewis and William Clark to traverse the continent until they reached the Pacific, studying everything from the ecology to geography along the way to get an understanding of the country's new region. Lewis and Clark would find far more than they anticipated. The 33 men who made the trip came into contact with about two dozen Native American tribes, many of whom helped the men survive the journey, and along the way they met and were assisted by the famous Sacagawea, who would become one of the expedition's most famous participants. Though they suffered deaths on their way west, the group ultimately reached the Pacific coast and got back to St. Louis in 1806, having drawn up nearly 150 maps and giving America a good idea of much of what lay west.

In the aftermath of the Louisiana Purchase, the Lewis and Clark expedition was a much-heralded blow for American rights in the face of international competition, but that was only one of four expeditions authorized by Jefferson. Given that Lewis and Clark remain so famous, it was inevitable that the other American explorers would be overlooked, particularly William Eaton, the hero of the Battle of Derna in the Barnaby Wars, and Zebulon Montgomery Pike, the explorer of the Mississippi.

Most of the most notable frontiersmen traveled immense distances during their careers, and for many, only distant memories could recreate the routes taken. Few of the significant wilderness figures were experienced as cartographers to create accurate maps for industry, settlement, and the military. These American frontiersmen made first contact with numerous indigenous tribes in virtually every area of the west, but viable maps were few. For example, historians believe that even Jim Bridger's prodigious travels were eclipsed by that of New York-born Jedediah Strong Smith, whose uncharacteristic personal life set him apart from the rough-edged mountain man reputation.

Of all the legends and folk heroes who lived in the 19th century, men such as Daniel Boone and Davy Crockett, few actually accomplished as much as Kit Carson. A frontier boy who hopped onto the Santa Fe Trail as a teen, Carson became the quintessential mountain man during the 1830s and was literally a trailblazer for John C. Fremont's historic expeditions through the West in the 1840s. Today, Fremont is best known for leading five expeditions west, three of which were official U.S. expeditions and two of which were private. On his third official expedition, he was given secret instructions for when he reached California.