Mental disability and voting for president

My wife’s brother John is 56 years old. John cannot read or write or do any kind of arithmetic. He can, with difficulty, scrawl a signature.

John works at Resources for the Disabled in Texarkana, Texas. He lives with my mother-in-law, who is 86.

Early in 2012, John brought home a list of his rights, as determined by the people who run Resources. Included was his right to handle his own finances, even though he cannot count, eben though he cannot tell the difference between a $5 bill and a $100 bill.

Resources also said John has the right to vote. Resources personnel are so convinced that John and others like him have the right to vote that they were teaching workers “how to vote.”

Along with the list of rights was a voter registration application. My mother-in-law filled out the form and mailed the application to the Bowie County offices. A short time later, John received his voter registration card.

As far as my mother-in-law knows, John did not vote in this month’s presidential election. She said, “He wanted to vote for Obama.” She also said several other workers at Resources, “who have the ability to understand things,” did vote.

How prevalent is voter registration for mentally challenged, mentally disabled men and women? Nationwide, how many voters, unable to read or write or even give an address or telephone number, were allowed to vote?