The Hartford Convention was an event in the United States during the War of 1812 in which New England's secession from the United States was discussed. It led to the demise of the nation's first political party, the Federalist Party.

Democratic-Republican President Thomas Jefferson's anti-foreign trade policies, particularly the Embargo Act of 1807 and Non-Intercourse Act of 1809, were very unpopular in the northeastern United States, especially among the wealthy merchants of Boston. Jefferson's successor, President James Madison, was even less popular in New England, particularly after his prosecution of the War of 1812, which disrupted international trade with England. When Madison was re-elected in November, 1812, the furor in New England intensified. Subsequently, the Federalist Party, formerly represented by statesmen like George Washington, John Adams, and Alexander Hamilton, became an opposition party, representing mostly New England and southern New York state.

On October 10, 1814, the Massachusetts state legislature called for the Hartford Convention, ostensibly to discuss several constitutional amendments necessary to protect New England's interests. On December 15, 1814, delegations from the then-five New England states (Maine at this point was still part of Massachusetts) met in Hartford, Connecticut. Official delegations were sent by Massachusetts, Connecticut, and Rhode Island. Delegations from New Hampshire and Vermont were from dissident counties; these two states were not as dependent upon foreign trade, or as culturally tied to Boston. Meetings continued in secret through January 5, 1815.

In all, twenty-six delegates attended. Largely due to the sensitive, many would say treasonous, nature of what was being discussed, no records of the proceedings were kept. In January, a final report was issued, containing language to the effect that New England had a "duty" to assert its authority over unconstitutional infringements on its sovereignty — a doctrine that would later reappear in a different context as "nullification."

The Hartford Convention's final report proposed several amendments to the United States Constitution. These attempted to combat the policies of the ruling Republicans by: 1) Prohibiting any trade embargo lasting over sixty days; 2) Requiring a two-thirds Congressional majority for any declaration of war, admission of a new state, or interdiction of foreign commerce; 3) Shifting the bulk of Federal tax payments to the slaveholding South; 4) Limiting future Presidents to one term; 5) Requiring each future President to be from a different state than his predecessor. (These last provisions were aimed directly at the ruling Virginia Dynasty.)

The Republican-dominated Congress would never have recommended any of New England's proposals for ratification. Hartford Convention delegates intended for them to embarrass the President and the Republicans in Congress—and also to serve as a basis for negotiations between New England and the rest of the country.

Hartford Convention delegates were apparently in favor of New England's secession from the United States, and either forming an independent republic, or reuniting with Britain. No such resolution was adopted at the convention; however, Massachusetts actually sent three commissioners to Washington, D.C. to negotiate these terms. When they arrived in February, 1815, news of Andrew Jackson's success at the Battle of New Orleans, and the signing of the Treaty of Ghent, preceded them and, consequently, their presence in the capital seemed both ludicrous and subversive. They quickly returned to Massachusetts. Thereafter, both the Hartford Convention and the Federalist Party became synonymous with disunion and secession, especially in the South. The Federalist Party was ruined as a national party, and survived only as a Boston-based party for several more years before vanishing entirely.