http://www.niu.edu/~rfeurer/labor/indexpage.html
British artist Walter Crane's "Labor's May Day," with its depiction of the worker as male, but united across nations and color lines, and inspired by freedom and entitled to leisure. May Day as a labor protest and was "invented" in the United States and celebrated as a day to rally for international labor solidarity.
The actual history of labor is a bit less male, and a lot more complicated! Still, the art is beautiful. The sentiment that human freedom might be achieved through the labor movement and radical change in economy inspired many labor activists, male and female, in the United States--across time and space.
This site is the most comprehensive bibliography of information, documents and links of U.S. labor history sites on the internet.
It was developed by labor historian
Rosemary Feurer for the Labor and Working Class History Association. If you know of sites that should be listed here, I will be glad to add them. Contact me

Named Best of the Web for The Gilded Age by Shmoop
Reference - Bibliographies
Teachers Corner – Lesson Plans and helpful links
Sites Organized Chronologically
Sites Organized Topically
Biographies and Oral Histories
Culture: Films, Songs, Literature, Art, Photos, and Other Media
Place/Space - museum listings, regional/state/local historical sites
Current Issues
Action alerts for labor history
Union sites with Historical content
Search (the site will be searchable soon)
So much more at link.