In the early years, 90 percent of the company's executives and supervisors were graduates of the Apprentice Training School and were either college graduates who had gone through a training program or had come up through the ranks. The firm’s turnover remained low. As Chicago became home to a northward migration of blacks, the workforce became stratified as non-whites found it hard to attain management positions. Racial tensions in the 1960s further weakened the company's ability to meet technological challenges and global competition. Declining fortunes led to layoffs and contention, and the school closed in 1993.