Can illegal voting really sway an election?

President-Elect Donald Trump claimed that three million votes in the United States were cast illegally. It is just the latest in a long line of unsubstantiated claims. Not only does he make the claim without citing evidence, he assumes that all illegal votes were against him. We know that's not true because Trump so thoroughly convinced some of his supporters that voter fraud was epidemic, they committed voter fraud to counteract the perceived injustice. However, just because Trump says whatever he wants without substantiation, does that mean no evidence exists? Regardless of whether Trump can back up his claims, is illegal voting a large scale issue in the United States? Virtually all claims of widespread voter fraud occur on right-wing websites. Even liberals who marched down the street tearing up property didn't believe voter fraud was a substantial issue. They just didn't like the election result. Almost all of the proposed evidence is generated by one side leadin