In 1892, Harper encouraged correspondence courses to further promote education, an idea that was put into practice by Chicago, Wisconsin, Columbia, and several dozen other universities by the 1920s. Enrollment in the largest private for-profit school based in Scranton, Pennsylvania, the International Correspondence Schools grew explosively in the 1890s. Founded in 1888 to provide training for immigrant coal miners aiming to become state mine inspectors or foremen, it enrolled 2500 new students in 1894 and matriculated 72,000 new students in 1895. By 1906 total enrollments reached 900,000. The growth was due to sending out complete textbooks instead of single lessons, and the use of 1200 aggressive in-person salesmen. There was a stark contrast in pedagogy: