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.
5. Railroad Shop Workers Strike of 1922 -- More than 400,000 railroad shop workers from a conglomeration of unions went on strike in July 1922 over a 7-cent cut in pay. They settled for a 5-cent pay cut and went back to work in October.