Aaron Burr's killing of Alexander Hamilton resulted in charges of murder which were (eventually) beaten, and Burr's strange adventure in the West that ended in (eventually beaten) treason charges.
Before his treasonous adventure Burr toured the West and was widely popular, with some newspaper editors thinking that he would settle in the West to restart his political career in friendlier territory. Burr could have settled down, made some friends, done some political organizing, and gotten himself a Senate seat somewhere in the West before the end of the 19th century's first decade.
Aaron Burr lived until 1836. What kind of effect would he have on American history if he began serving as Senator from Tennessee from 1809-1836?