The election between Thomas Jefferson and John Adams was a doozy, since each represented a political party that believed the other guys' victory would ruin the nation.
The sitting president, John Adams, was a Federalist who attacked Jefferson as a "howling atheist" whose sympathy for the French Revolution would bring chaos to the U.S.
Meanwhile, Jefferson and the Democratic-Republican Party denounced Adams' apparent love of federal power—particularly his expansion of the Army and Navy, plus new taxes and deficit spending. Jefferson described Adams as senile, vain, and driven by an "ungovernable temper."
Ultimately the Democratic-Republicans swept both houses of Congress, including a 65 to 39 majority in the House.
But the presidential election was another matter, with the electoral college tied between Jefferson and his running mate, Aaron Burr. A month after the election—and after a week of balloting—the House finally chose Jefferson.
Despite the rancor, it was the first peaceful transition of political power between opposing parties in U.S. history and therefore had far-reaching significance.