NAFTA has been hurting workers and the environment in the U.S., Mexico and Canada since January 1, 1994.
It is very unpopular for a variety of reasons. Trump campaigned against NAFTA. Now he is renegotiating it — perhaps with Mexico only instead of with all three nations because he has created conflicts with Canada.
A number of non-profit organizations have been working hard on issues related to “free trade” during these decades. One of the best is Public Citizen (www.citizen.org), which Ralph Nader had founded in 1971. Their top expert on the issue is Lori Wallach. Here is her article (dated Sept. 6, 2018) about what’s happening now with NAFTA: