There is a fine essay on labor history and the current problems of labor on our Democratic Left blog. here. http://www.dsausa.org/lump_of_coal_dl
Also see “How Dwindling Union Power Helped Usher In Trump”
Alan Draper American Prospect. http://prospect.org/article/how-dwindling-union-power-helped-usher-trump
Donald Trump swept the Rust Belt in part because labor unions are in retreat, a trend that started long before Election Day.