The labor contract between the International Longshoremen's Association and U.S. Maritime Alliance expired overnight on Tuesday. The ILA — whose members comprise dockworkers on the East Coast — is now officially on strike.

Supply chain disruptions stemming from a prolonged strike may affect several companies and the U.S. economy as a whole.

What Happened:The dispute stems from two fundamental disagreements between the stevedores and port employers.

In their collective bargaining agreement, the ILA proposed a 77% pay raise over the next six years. The USMX countered with 50%.

"Our offer would increase wages by nearly 50 percent, triple employer contributions to...