Negotiators from the United States and Mexico have reached a breakthrough on a key NAFTA sticking point. For months, Mexican and U.S. trade teams have been locked in talks in attempt to resolve demands from the United States that new automobiles contain a greater percentage of parts produced within the North American trade bloc and meet higher wage requirements in order to be traded without import tariffs under a renegotiated North American Free Trade Agreement (NAFTA). On Aug. 23, Mexican negotiators agreed that vehicles assembled at existing plants that do not meet new rule-of-origin percentages and wage requirements will be subject to a 2.5 percent tariff. Vehicles produced at yet-to-be-built factories will be subject to higher tariffs that will be determined by the White House upon recommendations by the U.S. Department of Commerce....