10 biggest strikes in U.S. history

POSTED: 08:21 AM PDT Sep 17, 2012    UPDATED: 07:47 AM PST Feb 02, 2015 
Oil fracking in California

The United Steelworkers union asked union workers at nine U.S. refineries to stop working after a national contract covering dozens of oil facilities expired on Monday. Take a look back at the 10 biggest strikes in U.S. history.