Matthew Green, the city councilor for the industrial area, has undisguised passion for the neighborhood and its history. It seems to be reciprocated.

When he walked into the Galley Pump Tavern, he was immediately recognized by a trio of stevedores who clearly had been spending considerable time toasting the summer weather on its rudimentary outdoor patio. One woman, seeing Mr. Green on the street, honked her horn and offered a fist salute as she drove past.

Mr. Green, the city’s first black council member, has said that three decades of free trade with the United States have been responsible for factory closings and exodus of jobs to the United States, particularly in his city.

Earlier this spring, a 107-year-old plant that made steel for the auto industry closed permanently after going into receivership and another steel maker said it was moving its Hamilton operation to Solon, Ohio.

“With Nafta, a lot of our jobs got sent down south and with them went the prosperity of our neighborhood, so we got hit pretty bad,” Mr. Green said. “So first they came for our jobs with free trade. And now with this tariff announcement it’s like they’re coming for our factories.”