MEXICO CITY — For Mexico, the United States-Mexico-Canada Agreement, an updated version of the North American Free Trade Agreement, is certainly better than having President Trump scrap the pact altogether, as he threatened to do in 2017. Beyond the debate about whether the agreement, which was finally approved by Congress recently and is to be signed into law by Mr. Trump today, has more pluses or minuses for Mexico, the real question is whether it can truly become a powerful lever for the country’s long awaited modernization. At a cost, it could.

The U.S.M.C.A. will put an end to the uncertainty that has rattled the Mexican economy since Mr. Trump became the Republican presidential candidate in 2016. Rules of trade, investment and intellectual property as well as dispute settlement mechanisms are enshrined in an international covenant, and not subject to the Mexican government’s whims. Most importantly, the labor and environmental provisions established in the pact will push Mexico to modernize its economy, work force and institutions over the next decade or so.

Rapid-response dispute-settlement mechanisms, international arbitration, the deployment of American so-called labor and environmental attachés in Mexico and placing the burden of proof on the party that is said to violate the agreement — not on the victim — may insure that Mexican workers will enjoy rights that they have never known in real life. The rules set out in the agreement include provisions for free elections by secret ballot for unions and their leadership, public posting of labor contracts on which union members are free to vote, multiple unions in each plant and transparency and accountability in union business.

Couldn’t Mexico achieve all of this on its own? The experience of the last century suggests otherwise. The agreement may be the equivalent of what the European Economic Community, the precursor to the European Union, meant militarily, socially and economically for countries like Spain and Portugal more than 30 years ago. In addition to labor rights, U.S.M.C.A. also lays out environmental regulations, although its silence on climate change is not encouraging, which several Democratic senators in the United States pointed out in voting against it.