The updat­ed ver­sion of the North Amer­i­can Free Trade Agree­ment unveiled this week does not rep­re­sent a clear improve­ment on the orig­i­nal 1994 deal.

There are changes for the bet­ter, like Mex­i­co’s agree­ment to adopt stronger pro­tec­tions for labor unions and Canada’s agree­ment to allow the sale of more Amer­i­can dairy prod­ucts. But there are also changes for the worse, like restric­tions on auto imports that will raise the price of new vehi­cles. And there are glar­ing omis­sions, notably the absence of a com­mit­ment to address cli­mate change.

The best argu­ment for pas­sage is pro­phy­lac­tic. Pres­i­dent Trump has threat­ened to aban­don NAFTA in the absence of a new deal, and the changes are less impor­tant than the part that would stay the same: a free-trade area for most goods encom­pass­ing the three largest nations of North Amer­i­ca.

The eco­nom­ic inte­gra­tion that fol­lowed the orig­i­nal deal was a jar­ring expe­ri­ence for many Amer­i­can work­ers and com­mu­ni­ties. But rebuild­ing trade bar­ri­ers, par­tic­u­lar­ly between the Unit­ed States and Mex­i­co, would for­feit the ben­e­fits of trade with­out revers­ing the dam­age.

On bal­ance, that is rea­son enough for Con­gress to pass the deal.

There is cer­tain­ly room to improve the orig­i­nal 1994 agree­ment, which shift­ed man­u­fac­tur­ing jobs to Mex­i­co in part by allow­ing com­pa­nies to take advan­tage of its low­er envi­ron­men­tal stan­dards and the weak­ness of its labor unions. The deal also pre­dates the Inter­net Age, and its out­dat­ed rules have con­strained the use of the inter­net to facil­i­tate cross-bor­der flows of goods, mon­ey and infor­ma­tion.

The new deal, called the Unit­ed States-Mex­i­co-Cana­da Agree­ment, rep­re­sents an improve­ment on both fronts. It incor­po­rates rules for the dig­i­tal econ­o­my sub­stan­tial­ly nego­ti­at­ed by the Oba­ma admin­is­tra­tion as part of its failed effort to cre­ate a broad­er Trans-Pacif­ic Part­ner­ship. And, at the behest of Amer­i­can trade unions and their allies in the Demo­c­ra­t­ic cau­cus, the deal also requires new pro­tec­tions for orga­nized labor in Mex­i­co, includ­ing the cre­ation of spe­cial­ized pan­els to adju­di­cate labor dis­putes.

The labor pro­tec­tions and strength­ened envi­ron­men­tal stan­dards are both nec­es­sary and mutu­al­ly ben­e­fi­cial — although they would have been far more con­se­quen­tial had they been includ­ed in the orig­i­nal agree­ment.

In some impor­tant respects, the agree­ment also improves upon the Trans-Pacif­ic Part­ner­ship. It dis­cards an effort by Amer­i­can phar­ma­ceu­ti­cal com­pa­nies to force Mex­i­co and Cana­da to adopt stronger restric­tions on gener­ic med­ica­tions. The indus­try argues that it would use the rev­enue to invest in inno­va­tion, but con­gres­sion­al Democ­rats right­ly insist­ed that hold­ing down drug prices is a high­er pri­or­i­ty.

The deal also sharply reduces the abil­i­ty of cor­po­ra­tions to seek con­ces­sions from nation­al gov­ern­ments through an extra­ju­di­cial sys­tem called “investor state dis­pute set­tle­ment.” The sys­tem amounts to a crow­bar that com­pa­nies have used to free them­selves from oblig­a­tions just­ly imposed by sov­er­eign nations.

Unfor­tu­nate­ly, these ben­e­fits are coun­ter­bal­anced by the Trump admin­is­tra­tion’s heavy-hand­ed efforts to revive Amer­i­can man­u­fac­tur­ing by reduc­ing for­eign com­pe­ti­tion.

The admin­is­tra­tion used the threat of end­ing NAFTA to extract agree­ment from Cana­da, and espe­cial­ly Mex­i­co, on a pack­age of pro­tec­tion­ist mea­sures designed to repa­tri­ate jobs in auto man­u­fac­tur­ing and asso­ci­at­ed indus­tries, like steel mak­ing. The rules, for exam­ple, require that a min­i­mum por­tion of the aver­age vehi­cle is pro­duced by work­ers mak­ing at least $16 an hour — far above wage rates in Mex­i­co.

The Unit­ed States Inter­na­tion­al Trade Com­mis­sion pre­dicts the mea­sures will suc­ceed in the nar­row pur­pose of shift­ing work to the Unit­ed States, but only at a high cost: Con­sumers will pay more for new vehi­cles, result­ing in few­er sales, and eco­nom­ic growth will suf­fer.

There is a broad­er threat, too. Shift­ing work to Mex­i­co has allowed Amer­i­can car com­pa­nies to reduce costs, and to com­pete more effec­tive­ly with for­eign pro­duc­ers. With­out NAFTA, there might be even few­er car-mak­ing jobs in the Unit­ed States today. And as a result of the changes, there may be few­er in the future.

The com­mis­sion still con­clud­ed that the new NAFTA would add $68.2 bil­lion to eco­nom­ic out­put, an increase of 0.35 per­cent. But its analy­sis rests on a pair of big assump­tions. First, the com­mis­sion assert­ed the deal would encour­age cross-bor­der invest­ment by eas­ing doubts about the sta­bil­i­ty of region­al trade rules. But one fea­ture of the new deal is an agree­ment allow­ing the Unit­ed States to with­draw after 16 years, which seems like­ly to have the oppo­site effect. The com­mis­sion also projects a big increase in e‑commerce, because the deal brings the NAFTA frame­work into the dig­i­tal age. But Mex­i­co and Cana­da already have sep­a­rate­ly adopt­ed the changes required by the deal.

Final­ly, the new deal amounts to yet anoth­er missed oppor­tu­ni­ty to forge the inter­na­tion­al coop­er­a­tion nec­es­sary to lim­it cli­mate change. More than 100 House Democ­rats signed a let­ter ear­li­er this fall seek­ing bind­ing com­mit­ments on cli­mate stan­dards as part of any revi­sions to NAFTA. But faced with the Trump admin­is­tra­tion’s will­ful refusal to address cli­mate change, Demo­c­ra­t­ic lead­ers decid­ed to pri­or­i­tize reach­ing a deal on oth­er issues.

The White House has described the result as “the biggest and best trade deal in the his­to­ry of the world.” It is more accu­rate­ly described as a minor deal that may do more harm than good. That it may also be the best pos­si­ble out­come under cur­rent man­age­ment is a reminder of the many ways in which Mr. Trump’s pres­i­den­cy con­tin­ues to ill serve the Amer­i­can peo­ple.