As far as I understand, with my poor otter brain, it hasn't. Further, if I recall correctly, adjusted for inflation (and not even purchasing power), the current minimum wage is under what it has been.
CNN has the numbers all of the way back to 1938 when the minimum wage was enacted. It looks like it's been up and down since then. The peak was in 1968 at $10.70 inflation adjusted and it's been roughly level since the early 80s.
http://money.cnn.com/interactive/econom ... ince-1938/
The biggest issue I have with a minimum wage increase is an order of addition problem. First do a stop loss on outsourcing jobs, Then raise the minimum wage.