Trump’s attack on North American Free Trade Agreement is over the top. It is often difficult to separate out the impact of trade agreements on jobs, compared to other, broader economic trends. But the nonpartisan Congressional Research Service in 2015 concluded the “net overall effect of NAFTA on the U.S. economy appears to have been relatively modest, primarily because trade with Canada and Mexico accounts for a small percentage of U.S. GDP,” though it noted “there were worker and firm adjustment costs as the three countries adjusted to more open trade and investment among their economies.”