Nearly half the containers that come into the U.S. go through West Coast ports. Giant ships bring cars, electronics and clothing in a surging trade with Asia that has tripled traffic at these 29 gateways. Now, a labor dispute between dockworkers and shipping companies threatens to shut down the ports. Some economists estimate this would cost the U.S. economy $2 billion a day. President Barack Obama has sent Labor Secretary Thomas Perez to San Francisco this week to try to broker a deal. But the two sides remain deadlocked. Diane and guests discuss what’s behind the West Coast port slowdown and what it could mean for the U.S. economy.