The Financial Post reports in its Wednesday edition that dockworkers on Tuesday walked out of every major port on the U.S. East and Gulf coasts, marking the beginning of a strike that could ripple through the world's largest economy. The Post's Laura Curtis writes that the affected ports have the combined capacity to handle as much as half of all U.S. trade volumes, and the strike will halt container cargo and auto shipments. Energy supplies and bulk cargo will not be affected. Some exceptions will be made to allow for the movement of military goods and cruise ships. The strike comes after dockworkers kicked off a three-day strike at the Port of Montreal on Monday. The significance of a work stoppage at every major container port from Houston to Miami and New York-New Jersey depends on how long the strike lasts. A backup resulting from a week-long strike would take a month to clear, according to Oxford Economics. The International Longshoremen's Association is seeking higher wages and a rollback of the language on automation in six-year contract that expired at midnight. Union leader Harold Daggett has for months threatened a strike. The last time East and Gulf coast dockworkers went on strike was in 1977.