Since the early 1980s, the U.S. economy has experienced a growing wage differential: high-skilled workers have claimed an increasing share of available income, while low-skilled workers have seen an absolute decline in real wages. How and why this disparity has arisen is a matter of ongoing...

In 2004, the European Union admitted 10 new countries, and wages in these countries were generally well below the levels in the existing member countries. Citizens of these newly-admitted countries were subsequently free to take jobs anywhere in the EU, and many did so. In 2015, a large number...