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.
2. The Pullman Strike -- Facing 12-hour work days and wage cuts, factory workers at the Pullman Palace Car Company in Chicago walked out in protest in May 1894. Railway workers grew their ranks to 250,000 strikers, effectively shutting down train traffic west of Chicago. Widespread sympathy to their cause promoted pro-union sentiment across many areas of the country.