A massive port strike up the East Coast that began on Tuesday has the potential to become one of America’s most disruptive work stoppages in recent times.

Long lines of container ships queued up outside major U.S. ports on Thursday as the biggest dockworker strike in nearly half a century entered its third day preventing unloading and threatening shortages of everything from bananas to auto parts.

A sweeping strike by tens of thousands of U.S. dockworkers came to a quick close late Thursday, with their union saying they would be back on the job Friday as they near an agreement with port operators and shipping companies.