April 7
National Labor Relations Board attorney tells ILWU members to “lie down like good dogs,” Juneau, Alaska - 1947
Some 300,000 members of the National Federation of Telephone Workers, soon to become CWA, strike AT&T and the Bell System. Within five weeks all but two of the 39 federation unions had won new contracts - 1947
And this:

April 7, 1947 - The National Federation of Telephone Workers conducted the first-ever nationwide strike against AT&T and the Bell System. At its peak, an estimated 300,000 telephone workers walked off their jobs. By May 18, all but two of the 39 member unions had won new contracts with substantial wage increases. A month later, the NFTW became the Communications Workers of America.

15,000 union janitors strike, Los Angeles - 2000
Labor history found here:
http://www.unionist.com/today-in-labor-history & here:
http://www.workdayminnesota.org/index.php?history_9_04_07_2011