Humanities › History & Culture Exploration of the West in the 19th Century Expeditions Mapped the American West Share Flipboard Email Print History & Culture American History America Moves Westward Basics Important Historical Figures Key Events U.S. Presidents Native American History American Revolution The Gilded Age Crimes & Disasters The Most Important Inventions of the Industrial Revolution African American History African History Ancient History and Culture Asian History European History Genealogy Inventions Latin American History Medieval & Renaissance History Military History The 20th Century Women's History View More By Robert McNamara History Expert Robert J. McNamara is a history expert and former magazine journalist. He was Amazon.com's first-ever history editor and has bylines in New York, the Chicago Tribune, and other national outlets. our editorial process Robert McNamara Updated June 30, 2018 At the very beginning of the 19th century, almost no one knew what lay beyond the Mississippi River. Fragmentary reports from fur traders told of vast prairies and high mountain ranges, but the geography between St. Louis, Missouri and the Pacific Ocean essentially remained a vast mystery. A series of exploratory journeys, beginning with Lewis and Clark, began to document the landscape of the West. And as reports eventually circulated of winding rivers, towering peaks, vast prairies, and potential riches, the desire to move westward spread. And Manifest Destiny would become a national obsession. Lewis and Clark The Lewis and Clark Expedition traveled to the Pacific Ocean. Getty Images The best known, and first, great expedition to the West was conducted by Meriwether Lewis, William Clark, and the Corps of Discovery from 1804 to 1806. Lewis and Clark ventured from St. Louis, Missouri to the Pacific Coast and back. Their expedition, the idea of President Thomas Jefferson, was ostensibly to mark out territories to help the American fur trade. But the Lewis and Clark Expedition established that the continent could be crossed, thus inspiring others to explore the vast unknown territories between the Mississippi and the Pacific Ocean. Zebulon Pike's Controversial Expeditions A young U.S. Army officer, Zebulon Pike, led two expeditions into the West in the early 1800s, first venturing into present day Minnesota, and then heading westward toward present day Colorado. Pike's second expedition is puzzling to this day, as it's unclear whether he was simply exploring or actively spying on Mexican forces in what is now the American Southwest. Pike was actually arrested by the Mexicans, held for a time, and eventually released. Years after his expedition, Pike's Peak in Colorado was named for Zebulon Pike. Astoria: John Jacob Astor's Settlement on the West Coast John Jacob Astor. Getty Images In the first decade of the 19th century the richest man in America, John Jacob Astor, decided to expand his fur trading business all the way to the West Coast of North America. Astor's plan was ambitious, and entailed founding a trading post in present day Oregon. A settlement, Fort Astoria, was established, but the War of 1812 derailed Astor's plans. Fort Astoria fell into British hands, and though it eventually became part of American territory again, it was a business failure. Astor's plan had one unexpected benefit when men walking eastward from the outpost, taking letters to Astor's headquarters in New York, discovered what would later be known as the Oregon Trail. Robert Stuart: Blazing the Oregon Trail Perhaps the greatest contribution of John Jacob Astor's western settlement was the discovery of what later became known as the Oregon Trail. Men from the outpost, led by Robert Stuart, headed eastward from present day Oregon in the summer of 1812, carrying letters for Astor in New York City. They reached St. Louis the following year, and Stuart then continued onward to New York. Stuart and his party had discovered the most practical trail to cross the great expanse of the West. However, the trail did not become widely known for decades, and it wasn't until the 1840s that anyone beyond a small community of fur traders began to use it. John C. Frémont's Expeditions in the West A series of U.S. government expeditions led by John C. Frémont between 1842 and 1854 mapped extensive areas of the West, and led to increased westward migration. Frémont was a politically connected and controversial character who picked up the nickname "The Pathfinder" though he generally traveled trails that were already established. Perhaps his greatest contribution to westward expansion was a published report based on his first two expeditions in the West. The U.S. Senate issued Frémont's report, which contained invaluable maps, as a book. And a commercial publisher took much of the information in it and published it as a handy guidebook for emigrants wishing to make the long overland trek to Oregon and California. The Gadsden Purchase Surveyors mapping the Gadsden Purchase. Getty Images The Gadsden Purchase was a strip of land in the American Southwest that was acquired from Mexico and essentially completed what would be the continental United States. The land was acquired largely because it was seen as a potential route for a transcontinental railroad. The Gadsden Purchase, when it was acquired in 1853, became controversial as it came to play a part in the great national debate over slavery. The National Road The National Road, which was built from Maryland to Ohio, played an important early role in the exploration of the West. The road, which was the first federal highway, was seen as vitally important when Ohio became a state in 1803. The country was faced with an new problem: it had a state that was very difficult to reach.