[Quoted from
Richardson 1917, p. 25]
There is indication that the blackboard was used in a few schools in the US before it was used at USMA. See Charnel Anderson, Technology in American Education, 1650-1900, published by the US Dept of Health, Education, and Welfare 1961 [Kent State: FS 5.234: 34018. Rickey has photocopy of pp. vi +16-25, 32-35, 40-47, 50-53; the last few pages are the bibliography of this small booklet.]
"George W. Cullum, USMA 1833, to his sister, Miss Catherine Cullum, April 24, 1831: Monday morning April 25th. – I have just returned from a hard morning's work, of surveying. I have been taking a plan of the point, for the sake of a little practice and still more for some fresh air. It is delightful working on the field instead of on the blackboard, particularly as we sometimes have a peep of some of the fair sex, when taking the positions of their dwellings." [Sidney Forman, West Point (1950), p. 98.]