One month before the 1860 election, Abraham Lincoln was clean shaven. By inauguration day, he had a full beard, and wore it until the day he died. He grew it because a twelve-year-old girl told him to.
I have yet got four brothers and part of them will vote for you any way and if you let your whiskers grow I will try and get the rest of them to vote for you you would look a great deal better for your face is so thin. All the ladies like whiskers and they would tease their husbands to vote for you and then you would be President.
He answered her letter, making no promises, but he must have stopped shaving almost immediately – because he won the election, and by inauguration day in March the next year he had his famous beard. On the way to Washington D.C. he stopped by Grace’s house and thanked her for the advice.
[Thanks to Nicoletta R. for suggesting this topic.]