Tens of thousands of dockworkers from ports spanning Maine to Texas walked off the job early Tuesday as they went on strike, demanding better wages and protections against automation. The strike comes as the contract between the International Longshoremen's Association union and U.

The dockworkers’ strike, their first since 1977, could snarl supply chains and cause shortages and higher prices if it stretches on for more than a few weeks. Beginning after midnight, the workers walked picket lines Tuesday and carried signs calling for more money and a ban on automation that could cost workers their jobs.