According to the literacy fast facts from the National Assessment of Adult Literacy (NAAL), literacy is defined as "using printed and written information to function in society, to achieve one’s goals, and to develop one’s knowledge and potential."
"One measure of literacy is the percentage of adults who perform at four achievement levels: Below Basic, Basic, Intermediate, and Proficient. In each type of literacy, 13 percent of adults were at or above Proficient (indicating they possess the skills necessary to perform complex and challenging literacy activities) in 2003. Twenty-two percent of adults were Below Basic (indicating they possess no more than the most simple and concrete literacy skills) in quantitative literacy, compared with 14 percent in prose literacy and 12 percent in document literacy."
Literacy statistics worldwide
Literacy statistics and juvenile court
Many of the USA ills are directly related to illiteracy. Just a few statistics:
Teaching reading skills is one of the best ways to save an aging brain
"Carlson is running a study called the Experience Corps Trial, in which older men and women volunteer to teach reading skills to kindergarten through third graders in Baltimore city schools. Using brain-imaging studies, Carlson and her colleagues have shown that after just a few months, people who volunteer show beneficial changes in their brains similar to those that other research teams have seen with exercise."