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...