Answer:
(Assuming you mean American Presidential Elections) I suppose because the 2000 election resulted in a ballot counting issue in Florida which resulted in the case being brought to the Supreme Court. Whoever won Florida would have won the election, and Democrat Al Gore was considered President-Elect for 37 days until the Supreme Court gave Florida to George Bush, officially confirming Bush as President-Elect.
2016 was notable because a lot of people thought many states such as Florida, North Carolina, Pennsylvania, Michigan and Wisconsin would all be called for Hillary Clinton, when in fact they were all called for Donald Trump, and it then became one of the biggest political upsets in American history.