Looking back, abundant data exist from states like Connecticut and Massachusetts to show that by 1840 the incidence of complex literacy in the United States was between 93 and 100 percent wherever such a thing mattered. According to the Connecticut census of 1840, only one citizen out of every 579 was illiterate and you probably don't want to know, what people in those days considered literate; it's too embarrassing.
Popular novels of the period give a clue: Last of the Mohicans, published in 1826, sold so well that a contemporary equivalent would have to move 10 million copies to match it. If you pick up an uncut version you find yourself in a dense thicket of philosophy, history, culture, manners, politics, geography, analysis of human motives and actions, all conveyed in data-rich periodic sentences so formidable only a determined and well-educated reader can handle it nowadays. Yet in 1818 we were a small-farm nation without colleges or universities to speak of. Could those simple folk have had more complex minds than our own? Excerpt from "Underground History of American Education," John Taylor Gatto.