Nearly 50,000 members of the International Longshoremen’s Association (ILA) are on strike Tuesday against the nation’s East and Gulf Coast ports, choking off the flow of many of America’s imports and exports in what could become the country’s most disruptive work stoppage in decades.

The port workers union is demanding a 77% wage increase over six years along with limits on automation, which it argues is hurting workers.

While many experts believe the up to $5 billion in daily losses to a strike can be absorbed for a week or so, damage to supply chains could get far heavier if the walkout extends further.