State Felon Voting Laws - Felon Voting - ProCon.org
As a group, southern states appear to be the most restrictive. Goes back to the conservative, authoritarian nature of religion, IMHO, which is of course not intended to "make sense". Also:
Misdemeanor Convictions (as of Apr. 8, 2010):
Anyone convicted of a misdemeanor in Idaho, Illinois, Indiana, Kentucky, Michigan, Missouri, South Carolina, and South Dakota may not vote while incarcerated. Kentucky and Missouri additionally require an executive pardon before allowing people convicted of certain misdemeanors ("high misdemeanors” in KY and "elections-related misdemeanors” in MO) from ever voting again. In Iowa, only persons convicted of an "aggravated" misdemeanor cannot vote while incarcerated.
Same link as above