Dockworkers at 36 ports across the eastern U.S. are now on strike for the first time in decades. And the work stoppage could snarl supply chains — leading to shortages and higher prices if it stretches on for more than a few weeks.

The 45,000 dockworkers who went on strike Tuesday for the first time in decades at 36 U.S. ports from Maine to Texas may wield the upper hand in their standoff with port operators over wages and the use of automation.

For the first time since 1977, 36 ports stretching from strategic seaboard locations as far north as Maine and as far south as Texas – all of which handle an aggregate $3 trillion in the country’s annual international trade – will be idle due to a work stoppage.