As far as global trade goes, "America First" may not necessarily mean "Louisiana First."

President Donald Trump, as promised, has already abandoned one big multilateral trade deal. And while details are still murky, he says he plans to fulfill his campaign pledge to renegotiate the long-standing North American Free Trade Agreement and slap tariffs on companies that move jobs out of the country.

Reciting a familiar refrain, Trump last week called NAFTA "a catastrophe for our country." His argument is that bad trade deals have shifted American jobs overseas, hitting especially hard in the upper Midwest, where thousands of manufacturing jobs have vanished in recent decades.

But if the result of Trump’s policy turn is ultimately a decline in global trade, Louisiana could wind up as collateral damage in the effort to shore up U.S. employment.

Among America's 100 largest metro areas, Baton Rouge ranks as the most dependent in the country on exports, which account for nearly a quarter of the area’s gross domestic product, according to a report last week by the Brookings Institution. Metro New Orleans ranks No. 3, with exports accounting for nearly one-fifth of its GDP, largely buoyed by the local port. 

"Outright protectionism keeps the pie really small, so trade and keeping trade open and expansive is incredibly important to Louisiana, in particular, since trade is the bedrock of our community," said Caitlin Cain, CEO of the World Trade Center New Orleans.

The nonprofit economic development group supported the now-abandoned Trans-Pacific Partnership — President Barack Obama's signature trade agreement between the U.S. and 11 Pacific Rim countries — because it would have offered Louisiana farmers more access to growing markets in Asia.

The pact, which never received congressional approval even before Trump officially killed it, would have eliminated more than 18,000 tariffs that various countries impose on American-made exports.

Renegotiating NAFTA, the 1994 agreement with Mexico and Canada, might be felt in Louisiana as well. Overall, trade among the three countries has climbed from $293 billion in 1993 to almost $800 billion last year. Mexico and China — another target of Trump’s vitriol on the campaign stump — are Louisiana’s top trade partners.

Mexico accounted for nearly $5.9 billion worth of exports from Louisiana in 2015. A 20 percent tariff on Mexican imports — an idea floated by Trump's spokesman last month — could put a huge damper on that trade.

"To see disruption of those activities is going to have significant ramifications to a lot of our businesses and a lot of our companies," said Louisiana Economic Development Secretary Don Pierson. "There's a lot to be mindful of right now."

"Without question, our economies are integrated," Cain said of Louisiana's relationship with Mexico. "A full-on divorce would be a very expensive endeavor."

Still, much depends on the details. And while Trump has railed against big, multilateral trade deals, he favors new agreements with individual countries, some of which could end up helping local industries that compete with imported products.

Some in Louisiana, for instance, are hoping for a trade deal with Vietnam that stipulates more rigorous safety testing of imported staples like shrimp. A higher bar could mean a reduction of imports, which could help prop up prices and make shrimp caught in Louisiana more competitive.

"We're looking forward to better access, improved markets and greater ability to move our products worldwide," Louisiana Agriculture Commissioner Mike Strain said last week about state-produced goods.

One aspect of Trump’s economic agenda that might actually help local exporters is the big infrastructure investment he has talked about. Louisiana officials are hopeful that if Trump follows through on his pledge to spend $1 trillion on such projects, the long-planned deepening of the lower Mississippi River to allow bigger cargo ships would be included.

"The more things we can export, the more people it takes to make those things, and that creates jobs," said Paul Aucoin, executive director of the Port of South Louisiana in LaPlace, the largest port in the U.S. by tonnage.

Whatever the outcome, which will depend heavily on what Trump is able to get through Congress, no one disputes that the impact in Louisiana will be deeply felt. In both Baton Rouge and New Orleans, trade has been a bright spot in an otherwise tough economic climate blamed in large part on slumping oil prices.

Robert Marionneaux, director of governmental affairs and outreach for the Port of Greater Baton Rouge, pointed out that his port in recent years has bolstered its business shipping wood pellets, which are largely exported to Europe for use as fuel. Last year, the port handled about 800,000 tons of them; this year, it could be closer to 1.5 million tons.

The Port of New Orleans handled a record amount of container cargo in the fiscal year ending in September: more than a half-million 20-foot equivalent units, or TEUs — a measure of cargo capacity for containerized shipping.

Over the first five months of 2016, chemical exports were up nearly 16 percent, making it the port's highest-performing commodity, and poultry exports climbed 41 percent as destination countries eased restrictions on U.S.-produced poultry.

On the imports side, the port saw coffee and non-ferrous metals — namely aluminum and lead — increase more than 12 percent.

Port officials are hoping politics don't get in the way of that.

"Any time you have people, politicians, anybody else interfering with trade and free market economics, there's always going to be disruption," said Robert Landry, the facility's vice president of commercial operations. "There's always going to be some unpredictability, and I think that's what we're seeing now."

Follow Richard Thompson on Twitter, @rthompsonMSY.