A historic strike is underway at U.S. ports — and the impact on global supply chains could be huge

A massive dockworker strike at seaports on the U.S. East and Gulf coasts is expected to wreak havoc on global supply chains and the economy, with American consumers likely to notice shortages of popular products if the work stoppage lasts for a long time.

Workers at ports stretching from Maine to Texas went on strike early Tuesday in a dispute over wages and automation. The action, which is likely to have severe consequences on ships carrying billions of dollars of cargo, is the first by the International Longshoremen’s Association (ILA) union in nearly half a century.

The ILA, which represents about 45,000 port workers, made good on its threat to strike at 14 major ports after talks broke down with the United States Maritime Alliance (USMX) employer group ahead of a Sept. 30 deadline.

“The top line takeaway here is duration amplifies impact,” Lisa DeNight, managing director of national industrial research at Newmark, told CNBC’s “The Exchange” on Monday.