The Louisiana Purchase nearly doubled the size of the United States at that time. It included the present-day states of Arkansas, Oklahoma, Missouri, Kansas, Iowa, and Nebraska. It stretched into parts of Minnesota, South Dakota, North Dakota, Montana, Wyoming, Colorado, New Mexico, Texas, and Louisiana.

The Louisiana Purchase also opened the Mississippi River to American commerce and travel. Historian Andrew O’Shaughnessy says that as a result of this access, the Louisiana Purchase fueled the country’s economic expansion in the nineteenth century. And, Mr. O’Shaughnessy says the Louisiana Purchase created more opportunities for Americans to own land.

“It was very important to Jefferson because he really wanted every free member of society to be able to own land. He regarded land ownership as in many ways essential to someone’s independence and their ability therefore to participate in a republican government.”

But both Mr. O’Shaughnessy and historian Joseph Ellis say the Louisiana Purchase went against Jefferson’s beliefs about central government. Joseph Ellis says that in many ways, Jefferson’s presidency aimed to make the federal government almost invisible and to limit the president’s power.

“And the Louisiana Purchase is the most authoritative executive action in American presidential history. One president decides to buy the Midwest. And he does it unilaterally.”