Need workers? Tight labor markets have become a problem for US employers faster than anyone expected. Unemployment dropped to 5.3 percent in June, thanks to boomer retirements and a productivity slump that forced companies to add new workers. Unemployment shows signs of dropping even further, possibly to 4 percent by mid-2017, a rate reached just once since 1970. What does this mean for employers? Difficulty hiring and retaining qualified workers, and wage growth that may further cut corporate profits, are on the horizon.