Dockworkers at 15 ports from Texas to Maine were all but certain to go out on strike early Tuesday, a move that could raise prices on goods and cause shortages and price increases as the holiday shopping season approaches.

The biggest dockworker strike in almost half a century is on its third day. If talks continue to stall for weeks, delaying the unloading of goods, it could spell trouble for at least one major retailer in Texas.