Morris Kleiner discusses the history of workforce licensing.
This might be a fairly minor matter, were it not part of (yes) a larger trend. In a 2010 paper published in the British Journal of Industrial Relations, Morris Kleiner of the University of Minnesota and and Alan Krueger of Princeton note that less than 5 percent of the U.S. workforce was required to be licensed in the 1950s. By 2000 the figure had surpassed 20 percent and now stands just shy of 30 percent. The result: higher prices - and economic sclerosis.