On a recent evening as bundled runners hustled along Canton Waterfront Park, two massive car-carrying ships were visible in the distance, berthed at a Port of Baltimore terminal.

One of those vessels, the Grande Portogallo, was filled with brand new automobiles from Mexico. President-elect Donald Trump has threatened a host of tariffs on foreign countries, including an immediate 25% tariff on Mexico and Canada and an extra 10% on China.

Tariffs on those countries, the U.S.’s top three trade partners, are the stuff of economists’ nightmares and would have far-reaching effects on the American economy — and on the Port of Baltimore and the regional economy.

Baltimore is home to the busiest car port in the world’s top car-importing nation. And no country sends more cars to Baltimore than Mexico, which has become a manufacturing hub for companies like Volkswagen, Mazda and Nissan. Mexico accounts for 29% of Baltimore’s auto imports, more than Germany’s 22% and Japan’s 20%.

Nearly one-quarter of all tonnage (not just cars) shipped into Baltimore’s port comes from China, Mexico or Canada, which all rank in the top four among nations shipping to Baltimore. Brazil ranks first. Steeper tariffs could slow some of that port traffic.

“[Tariffs] would have a negative impact on the local economy, the Maryland economy, and I think, throughout the U.S., it would slow down growth,” said David Kass, a professor at the University of Maryland’s Robert H. Smith School of Business.

Before Trump introduced tariffs in 2018 — which President Joe Biden then continued — tariffs were seldom part of U.S. policy. They had a pop culture cameo in 1986, when a high school teacher portrayed by Ben Stein tried to lecture a bored Matthew Broderick in “Ferris Bueller’s Day Off” about the 1930 Smoot-Hawley Tariff Act.

That 1930 law, which economists warned then-President Herbert Hoover against before implementation, prompted retaliatory tariffs, decreased world trade and worsened the effects of the Great Depression, historians say. It also saddled tariffs with a bad reputation, which Trump, who once tweeted “I am Tariff Man” and dubbed tariff “the most beautiful word in the dictionary,” has tried to rehab.

Trump sees tariffs as a multiurpose tool. He says he’s using them as a threat to Canada and Mexico to curb undocumented immigrants and fentanyl crossing the border into the U.S. Tariffs would encourage foreign businesses to manufacture in the U.S., he says, and also generate federal revenue. Economists warn that any monetary benefits would be washed away by other negative effects.

During his first term, Trump implemented mild tariffs. His current suggestions would be significantly stronger. This time, he will likely have buy-in from the Republican Party, which will control both chambers of Congress next month. That means more extensive tariffs have a shot at becoming U.S. policy.

Some businesses may be reacting to the news of potential tariffs by stockpiling goods now, before a potential increase in the cost of imports. Trump’s inauguration on Jan. 20, as well as the potential of an East Coast port strike on Jan. 16, seem to have precipitated a flurry of shipments, including into Baltimore.

“The nation’s major container ports are expected to see a continued surge in imports through next spring,” according to a news release this month from the National Retail Federation.

The Port of Baltimore, which is recovering from the Francis Scott Key Bridge collapse, has seen a steady increase in traffic since the shipping channel re-opened in June. Jonathan Daniels, executive director of the Maryland Port Administration, said the port should be fully recovered in the first few months of the new year.

The port has been particularly active in recent weeks. Cargo ships require at least one tugboat to move in and out of berths in Baltimore, and McAllister Towing, one of the two companies that provides service in the port, said November was its busiest month in recent memory.

It is difficult to tease out precisely why that might be. Market factors and altered shipping lines, in addition to possible tariffs and a looming strike, are at play, experts say.

“It’s hard to ultimately know whether any type of flurry that’s occurring throughout the United States right now is pinned to the potential for tariffs, especially considering that there could be another shutdown of Gulf Coast and East Coast ports going into the middle of January,” Daniels said.

The Port of Baltimore handled about 850,000 automobiles and light trucks, most of which were imported, in 2023, the most of any U.S. port for the 13th straight year. Meanwhile, the Port of Brunswick near Savannah, Georgia, is nipping at Baltimore’s heels for the No. 1 rank.

“[Possible tariffs] could lead to a smaller amount of vehicles and throughput coming through, but that’s something that would impact all ports that handle vehicles,” Daniels said.

The Mexican peso and Canadian dollar have dropped in value against the American dollar since Trump won the November election and doubled-down on tariff talk. But it remains to be seen how serious his threats are — and how much may simply be a negotiating tactic.

Some business owners aren’t sure what to make of his claims. Kristi Simon, president of the Howard County Chamber of Commerce, said that while some members have expressed concerns, others feel the tariffs are unlikely to happen or that implementation would be years away.

Sylva Lin, who owns Culinary Architecture in Pigtown, said her speciality foods store is taking a “wait and see” approach given potential tariffs. If import prices do increase, she said, she plans to redouble her efforts to find locally sourced products.

When Trump levied tariffs on China in 2018, the Port of Baltimore felt the impact.

Chinese imports to Baltimore dropped from 1.5 million tons in 2018 to 1.2 million tons in 2019 — a 20% decline. That figure hasn’t fully bounced back; China sent 1.3 million tons to Baltimore.

“It didn’t grow back to the level of where it was,” Daniels said.

Economic impacts have a way of creating a domino effect. Fewer cars being shipped to Baltimore, for example, could mean fewer working hours for the longshoremen who drive the vehicles off the ships, fewer trips for truckers, and more expensive car purchases for the American consumer.

Plus, tariffs can snowball. The interdependence of each country’s supply chain means that cars sometimes cross borders seven or eight times during their assembly process, according to a 2021 report to federal lawmakers. Under potential tariffs, each time they cross the border into the U.S. from a neighboring country, in theory, they could be taxed.

The Grande Portogallo car carrier that pulled into the Fairfield Terminal last week had previously visited Baltimore in late November, according to marine tracking data.

It then sailed to two ports alongside Mexico’s eastern coast in December, before it made a four-day voyage back to the U.S., stopping first in Brunswick and then Baltimore, to offload cars.

“[Tariffs] could have a spiraling effect and slow down the economy even more. And add to inflation. It is really, very bad economics,” Kass said.