In loving, living memory, John Melançon 1928 – 2007
More than two percent of otherwise eligible-to-vote citizens of the United States of America are denied the right to vote for felony convictions.
In total numbers and in the political tendencies of the disenfranchised, that's about the same as denying Jews the vote in the U.S.
in 1998 "an estimated 3.9 million U.S. citizens are disenfranchised, including over one million who have fully completed their sentences."
The figures are probably worse now, although there's been more publicity about (and legal improvements in) paths to regaining your right to vote since 2000.
"Thirteen percent of African American men—1.4 million—are disenfranchised, representing just over one-third (36 percent) of the total disenfranchised population."
The disenfranchised, of course, are still counted for states' and towns' representation weight in congress and legislatures. They just can't vote.
The prison system isn't regarded as the new slavery for nothing.
In Southern states this is literally how Republicans (and before them Democrats/Dixiecrats) stay in power, at least in some counties-- as blacks won the right to vote, these states were most aggressive in taking the vote away from felons, and among the most racist in who received felony convictions.
Human Rights Watch in its report - http://www.hrw.org/reports98/vote/usvot98o-01.htm
Felony disenfranchisement and the chilling effect on people who may no longer be disenfranchised or may not have any conviction (or in the case of Florida were purposefully stripped off the roles for having a name and race similar to convicted felons) certainly can affect elections.
Mississippi listed 145,600 in 1998 and about the same in 2004, the McCain margin over Obama margin was slightly higher at 166,708.
Missouri disenfranchised 58,800 felons at the time of the report, 20,100 black men, which is quite low for the total population compared to many other states– but there the latest election is listed as McCain ahead of Obama by just 5,859.
Perhaps, if everyone could vote, McCain's 173,262 vote edge in his own state of Arizona would have been erased by the 176,101 disenfranchised people in prisons and jails, on parole and probation, or who are former felons. (Disenfranchisement numbers circa 2004 http://www.sentencingproject.org/StatsbyState.aspx )
The Georgia senate race, with about 111,000 votes separating the evil Saxby Chambliss from the less evil Jim Martin, may have been decided differently if not for 283,607 disenfranchised voters, more than half of them black. (And the reported McCain lead over Obama in Georgia was 206,589 votes.)
I'm sure it gets even more interesting in state legislatures and U.S. House of Representatives districts, but the effect on any given election isn't the point. The point is that if the fundamental right to vote is taken away from anybody – let alone more than two percent of the adult population in a racially discriminatory process – we don't have a democracy.