America Heads West

How Lewis and Clark—along with a Native American guide, Sacagawea—explored the newly expanded United States

On a gloomy December afternoon in 1803, a boat crept along the banks of the Mississippi River and landed at the mouth of the Wood River in what is now the state of Illinois. A group of men climbed out and began to set up camp under a dark canopy of oak trees. Suddenly a violent storm moved in, pelting the area with snow and hail.

The men didn’t turn back though. Instead, they hunkered down and spent the next five months here preparing for the trip they were about to embark on,in which poor weather would be one of the many dangers they’d face.

Among these men were Meriwether Lewis and William Clark, co-leaders of an expedition tasked with exploring land that the United States had recently acquired. Their trip would turn into an epic 8,000-mile-long trek—and the first big step in the United States’ westward expansion.


When Thomas Jefferson became the third president of the United States in 1801, the country basically stopped at the Mississippi River. France controlled much of the land to the west of this waterway.

President Jefferson wanted to acquire the Port of New Orleans, in what is now the state of Louisiana, from the French. Its prime location made it a key spot for trade. In 1803, Jefferson made what’s known as one of the greatest real estate deals in history: the Louisiana Purchase.

After negotiations, France agreed to sell the entire city of New Orleans, which included the port, to the United States for $10 million; they threw in the rest of the territory they owned for an additional $5 million. The agreement—which gave the United States approximately 828,000 square miles of land—almost doubled the size of the nearly 30-year-old nation.

The United States only paid about three cents an acre for the land, which stretched from the Mississippi River in the east to the Rocky Mountains in the west and from the Gulf of Mexico in the south to the Canadian border in the north. Spain still owned much of the southwestern part of what’s now the United States, stretching from the area that would become Texas to present-day California.

Purchasing this enormous amount of land was one thing, but exploring it was another. Jefferson wanted to plan an expedition to investigate the territory. He called the proposed mission the Voyage of Discovery and began assembling a team of explorers called the Corps (KOR) of Discovery. The president chose Captain Meriwether Lewis and Captain William Clark to lead the expedition. Lewis, President Jefferson’s personal secretary, was an officer in the United States Army and spoke several Native American languages. Lewis recommended Clark—a retired officer who had served alongside him in the Army—as the expedition’s co-leader.


In the spring of 1804, Lewis, Clark, and dozens of other men left St. Louis, Missouri, by boat. They traveled westward through what is now Missouri, Iowa, Nebraska, and South Dakota.

In November they reached Knife River Village in present-day North Dakota. There they met a young Shoshone Native American woman called Sacagawea (Sa-kuh-juh-WEE-uh) and her fur-trader husband, Toussaint Charbonneau (Too-SAHNT SHAR-bon-oh). The couple joined the expedition as interpreters, translating the language of the local tribes for Lewis and Clark’s men.

Sacagawea didn’t just serve as an interpreter during the trip, however. She helped Lewis and Clark’s men obtain essential supplies and horses, identified edible plants and herbs, and prevented hostile relations with other tribes simply by being with the group—all while carrying her newborn baby on her back.

After meeting Sacagawea and her husband, the Corps traveled west from North Dakota, 15 to 20 miles a day on foot and by boat, toward the mountains. Day after day, the exhausted, freezing team braved rough rivers and perilous peaks, getting by on very little food. They wouldn’t see the Pacific Ocean until November 1805—over a year after they first left Missouri.


After a long winter waiting out the bad weather, the Corps was able to start making their way back east in March 1806. After returning Sacagawea and her husband to North Dakota, the remainder of the Corps arrived back in Missouri in late September, more than two years after they started their expedition.

Lewis and Clark’s team mapped uncharted land, rivers, and mountains. They brought back journals filled with details about Native American tribes and scientific notes about plants and animals they’d never seen before. They also brought back stories—tales that made other Americans dream about heading west.

Many Americans did more than dream. The great westward expansion was about to begin.

Text adapted from The Journals of Lewis and Clark; The Mississippi and the Making of a Nation: From the Louisiana Purchase to Today; and Sacagawea