More than a hundred truckers who work at the ports of Los Angeles and Long Beach are on strike, calling for better pay and safety and accusing transport companies of hindering their efforts to unionize. The trucking companies say they pay fair wages and that drivers striking are only a small slice of the total workforce.

It’s the latest workforce disruption at an important trade gateway with a long history of labor unrest.

The ports are a key point for trade with Asia, with hundreds of billions of dollars in goods moving through. You probably own something with a “Made in China” label, and it most likely came through these California ports.

Right now, only three trucking companies are affected by the strike. Others are still rolling. The picketing isn’t large enough to cause a major disruption.

But if dockworkers walk off the job in support of the truckers, it could snarl trade, with nationwide impact if the strike drags on.