U.S. ports from Maine to Texas could shut down Tuesday if a union representing about 45,000 dockworkers carries through with a threatened strike. A lengthy shutdown could raise prices on goods around the country and potentially cause shortages and price increases at big and small retailers alike as the holiday shopping season — along with a tight presidential election —

Tens of thousands of longshoremen went on strike at midnight ET, shutting down major ports along the East and Gulf coasts and choking off deliveries of everything from produce to auto parts.