What determines labor productivity?

"In the early 1980s, as a result of unprecedented developments in the world steel market, iron-ore was entering the Great Lakes from as far away as South America.The Great Lakes regional producers, that is, the U.S.and Canadian iron-ore industries, faced a major crisis that cast doubt on their future.In response to the crisis, these iron-ore industries dramatically changed how they produced iron-ore, in the process doubling their labor productivity and pushing foreign competition out of the Great Lakes.I show that most of the productivity gains were due to changes in institutional rules, and most importantly in work rules, that governed how production took place"--Federal Reserve Bank of Minneapolis web site.