The last time members of the International Longshoremen’s Association (ILA) shut down ports up and down the East and Gulf coasts, it was 1977, and dockworkers wanted higher wages and greater job security. New technology — specifically containerization, which transformed the industry — introduced uncertainty into the craft, and the longshoremen who handled freight wanted to be sure that any disruptions introduced by the shifting mechanisms on the ports wouldn’t lead to their permanent displacement.

Trade was only 16 percent of the US economy back then, well below today’s 27 percent. Yet the work stoppage, which lasted forty-five days, was earth-shattering. Shippers said some $4 billion worth of cargo piled up at the thirty affected docks. Other businesses and trucking companies laid workers off as the slowdown reverberated throughout the economy. In Puerto Rico, which relies on imports for the vast majority of its food, importers began bringing groceries in by air. The union proved largely victorious, winning increases in wages and benefits as well as greater job security.

Nearly half a century later, wages and job security are once again at the center of a port shutdown that will snarl supply chains and send shockwaves through the US economy, costing anywhere from hundreds of millions to several billion dollars per day.