Robert Livingston negotiated in France for control of the Louisiana territory. Napoleon agreed to sell all of the Louisiana territory plus New Orleans. On April 30, 1803, US bought Louisiana from France for about $15 million. US gained full control of the Mississippi River and doubled its size.
Hamilton Vs. Burr
In May 1804, Meriwether Lewis and William Clark headed west towards the Missouri River. The expedition gave the US knowledge of the Rocky Mountains and the Louisiana territory.
After the Louisiana Purchase, New England federalists knew that their region would lose its influence in national affairs. The South and West would gain political power sso the group of federalists known as Essex Junto wanted New England out of the union.
Essex Junto persuaded Aaron Burr to to run for governor because they wanted to spread their plan. Hamilton called Burr a dangerous man so Burr challenged Hamilton to a duel. In the end, Burr shot and killed Hamilton.
Jefferson didn't want America to get involved in a war so he asked congress to stop trade between the US and Europe by passing the Embargo Act. The Embargo Act hurt the American economy and congress repealed it after Jefferson's first term ended.
In 1807, Madison was elected as the next president. He also wanted to prevent war so he asked congress to pass the Non-Intercourse Act which was the Embargo Act but it also gave the president the power to reopen trade restrictions with whichever country removed their trade restrictions.