On July 11, General Alexander Hamilton (former Secretary of the Treasury) and Colonel Aaron Burr (current Vice-President) met for a duel to settle their long-standing and ever-growing hatred for one another. Hamilton was leader of the Federalist Party and mastermind of politics and had recently given support to the opposing Morgan Lewis specifically to make Burr lose his bid for Governor of New York. Burr had been dropped from Jefferson's ticket in the 1804 election and had planned to secure more local political action, but now he only had rage against Hamilton.
Hamilton continued working to wrest power from the “dangerous” Democratic-Republicans he feared would turn the United States into a mob of rabble. Jefferson won his second term in 1804, and his protege and Father of the Constitution James Madison would take the election of 1808. In 1812, the political climate would changed. Europe was embroiled in the Napoleonic Wars, which threatened to drag in the US as well with English as well as French naval ships plundering American vessels and “impressing” sailors into service.
War Hawks called for a campaign against Britain and even an invasion of Canada in the spirit of expansionism (which many thought would be easily done with local support; Jefferson said it was a “mere matter of marching”). President Madison set an ultimatum that both France and Britain recognize their neutrality or face war. France sent communications (eventually proven misleading) that they would, and Congress very nearly declared war on Britain but for the political finagling of Hamilton. Without his war and the growing political discontent, Madison would lose the 1812 election to DeWitt Clinton of New York, the first Federalist president in twelve years.
Clinton called for a strengthening of America's infrastructure, building roads that would lead to and aid in the later Indian Wars. As a member of the Erie Canal Commission, which others would see through with his assistance. Further, and perhaps most importantly, Clinton set to solve the problems of international quarrels by improving the navy of the United States beyond Jefferson's pocket-boat defense. Now a force to be reckoned with, Britain and France would recognize American neutrality, and after the defeat of Napoleon, a war-beleaguered Britain would sign the Treaty of Ghent with America, solving the issues that could have started a war only two years before.
The Federalist Party would continue to challenge the Democratic-Republicans, though both would agree on the Monroe Bill (named after Senator Monroe of Virginia) that the US would not abide European interference in the Western Hemisphere. As the Spanish Empire collapsed to the south, Americans welcomed the growing Republicanism and used its fleet to dissuade Europe from further colonization. America itself would assure dominance with the Mexican War in 1846, but be true to Monroe's word in 1861 by aiding Mexico in overcoming the French and Spanish invasion by Maximilian (which also relieved growing tension on the question of slavery, later to be solved by the 1867 Emancipation Proclamation, promising ample government compensation to any owner willing to free his slaves).
Pushing West and now south, American expansionism turned to annexing turbulent Latin American nations in the latter half of the nineteenth century. While accusations of “empire” were made and perhaps deserved, America grew powerful in the Western Hemisphere and increasingly Hispanic in background, creating a vivid diversity that would supply ample raw materials and labor for an Industrial Age. As the Cold War raged with the Soviet Union in the next century, America would see many of its states and territories fighting for their own independence fueled by Communist insurgents, igniting a Civil War over the question of states' rights.
In reality, Hamilton would die of his wounds, which were tremendous as Burr's shot has ricocheted within the man's torso. Without a strong leader, the Federalist Party would fall behind the Democratic-Republicans, eventually leading to the Era of Good Feelings, an age downplaying partisanship under President Monroe where the Federalists would all but cease to exist.