The “demographic cliff” is upon us. The number of teenagers graduating from American high schools peaked last year. It will begin declining this spring and keep falling steadily through at least 2041. The trend is more of a downward slope than an abrupt falloff, but the gradient is steep and represents a crisis to colleges dependent on filling classroom seats and dorm beds. The United States currently has about 4,000 colleges. According to a recent study from the Federal Reserve Bank of