Louisiana Purchase: Thomas Jefferson's acquisition of a vast territory from France in 1803 through diplomacy and negotiation. This expanded the size of the United States and offered new opportunities for agrarian expansion.
Embargo Act of 1807: A law passed under Jefferson's presidency that banned American ships from trading with foreign nations in an effort to protect American interests. It aimed to avoid war but ended up damaging the U.S. economy instead.
Marbury v. Madison: A landmark Supreme Court case that established judicial review, giving courts the power to declare laws unconstitutional. This decision reinforced the principle of checks and balances within Jefferson's vision of limited federal government power.