What major purchase did the United States make under President Thomas Jefferson?

The major purchase made by the United States under President Thomas Jefferson was the Louisiana Purchase. This significant land acquisition from France in 1803 effectively doubled the size of the United States, adding approximately 828,000 square miles of territory. The purchase was pivotal for several reasons: it provided vast expanses of land for settlement and agriculture, it opened up new opportunities for exploration and trade, and it established a precedent for future land acquisitions.

The Louisiana Purchase set the stage for westward expansion and was pivotal in shaping the nation's geographical and political landscape. This acquisition also aligned with Jefferson's vision of an agrarian America and his belief in the importance of land ownership for individual liberty and democracy. The deal, valued at about $15 million, was not only a financial transaction but also a transformative moment in American history.