November 20
First use of term “scab,” by Albany Typographical Society - 1816

Lexicon of Labor is an invaluable resource for all unionists, from rank-and-file activists to newsletter editors to union leaders. It offers readable, informative descriptions of more than 500 key places, people and events in American labor history, from explaining who the Wobblies and Knights of Labor were to reporting on the 1997 Teamster strike at UPS. This revised and updated edition includes dozens of new terms and developments and introduces a new generation to the labor lexicon. In The UCS bookstore now.
Norman Thomas born, American socialist leader - 1884
The time clock is invented by Willard Bundy, a jeweler in Auburn, N.Y. Bundy’s brother Harlow starts mass producing them a year later - 1888
Mine fire in Telluride, Colo., kills 28 miners, prompts union call for safer work conditions - 1901
78 miners are killed in an explosion at the Consolidated Coal Company’s No. 9 mine in Farmington, W. Va. - 1968
And this:

November 20, 1968 - An explosion at the Consolidated Coal Company’s No. 9 mine in Farmington, West Virginia, killed 78 miners, giving rise to a United Mine Workers Union campaign for federal coal mine safety legislation.
Labor history found here:
http://www.unionist.com/big-labor/today-in-labor-history & here:
http://www.workdayminnesota.org/index.php?history_9_11_20_2011