These five maps look at how the 2012 election would have played out before everyone could vote.
This series of maps shows that election of 2012 would have looked very different if the voting laws had not changed. The African-American, female and young (18-21) have all not been able to vote in the U.S. and all three are key constituencies of President Obama. However, these maps are assuming the same percentages of today held true for back then. The white population is a declining share of the U.S. population. I remember seeing (somewhere) that if the demographics of the U.S. were today what they were in 1996, he would've won the election. Here is a related article on the changing demographics of the electorate.
Via Seth Dixon, Matthew Wahl