We have argued that a voter ID requirement is a bad idea because it would exacerbate two problems Pennsylvania already has (voter turnout and a budget deficit) in an attempt to fix a problem we don't have (voter fraud).
In the midst of a post about how voter ID requirements would also make voting take longer (and probably harm turnout as a result) Dave Davies explains why voter fraud isn't a common problem:
While political operatives will look for every advantage and some will break the law to win elections, I have to believe that sending people to polls to impersonate someone else is a pretty rare kind of fraud.
Think about it. How many people can you get to risk federal prosecution by walking into a polling place and pretending they're someone they aren't, to get a single illegal vote?