NAFTA is still controversial. First, the U.S. lost many manufacturing jobs to lower-cost Mexico. Second, workers in jobs that weren't outsourced had to accept lower wages. Third, Mexico's workers suffered exploitation in its maquiladora programs. For more, see NAFTA's disadvantages.
Yet, U.S. grocery prices would be higher without tariff-free imports from Mexico. It's also clear that imports of oil from both Canada and Mexico prevent high gas prices.