The amount of genealogical information you can find on unionized ancestors partly depends on how active they were in their union. Every member would pay dues and be listed in membership records, while organizers would be mentioned in applications, correspondence and reports. Union newspapers, newsletters and bulletins are other sources of information on both organizers and regular members.
To which union did my ancestor belong?
There are several methods you can use to track down which union your ancestor belonged to. The easiest, and probably the most efficient, is to ask relatives. If I had a dime for every time my husband told me that his grandfather was a Teamster, I'd be rich. But keep in mind the pitfalls of family (mis)remembered information, and also ask for the specific occupation and workplace of the person you're researching, so you can confirm the information. Also, if Grandpa really was a Teamster, knowing the specific workplace will help you nail down the local he belonged to.
Another method is to look through photos, correspondence, and belongings. In his or her time with a union, a person would have attended meetings and possibly picnics or other social gatherings. Years in the union would also mean accumulating notices, newsletters, membership cards, baseball caps, t-shirts, pins, pens, signs and stickers.
If you're really stuck, find out the occupation and location of your ancestor and work from there. An electrician, for example, may have belonged to the United Electrical, Radio, and Machine Workers of America (UE) or the International Brotherhood of Electrical Workers (IBEW). The AFL-CIO website at http://www.aflcio.org lists contact information and websites for the 55 unions affiliated with it, and is one place to start.
How can I access more information?
If you know the union and the workplace/location of your ancestor, you can find the local. Once you know the local you could contact them directly to see what's available. If you can't find the local, you can try contacting the union at the district level.
Alternatively, there are two resources of labor union history available to the public: The Walter P. Reuther Library of Labor and Urban Affairs at Wayne State University in Michigan, and the Archives of Industrial Society at the University of Pittsburgh.
The Walter P. Reuther Library of Labor and Urban Affairs
The Reuther Library describes itself on its website as "the largest labor archive in North America." It houses records on many unions, including the United Auto Workers (UAW), the Industrial Workers of the World (IWW), and the Service Employees International Union (SEIU). Records include membership lists, dues and bulletins from some locals, as well as historical documents on the labor movement. It is open to "anyone engaged in serious research"; potential visitors are asked to call, write, or email in advance.
Does the Reuther Library have what you need? Check out their website at www.reuther.wayne.edu. Quick links on the left-hand side let you check the collection by several unions (UAW, IWW, SEIU), while the "browse by all: categories" offers a broader search of the collection. The "collections" tab near the top of the page lists all holdings alphabetically. The library's home page also serves as its blog, with posts on labor history and updates on the collection holdings.
The Archives of Industrial Society
The Archives of Industrial Society, part of the Archives Service Center at the University of Pittsburgh's University Library System, houses many union records with an emphasis on Pittsburgh and western Pennsylvania; it also houses the official records for the UE at national, district and local levels.
Visiting the AIS page at www.library.pitt.edu/libraries/archives/ais.html allows you to enter keywords in a search box on the right-hand side of the page to search the collection guides, as well as an option to browse the collection guides. The search option takes you to the University of Pittsburgh Library System digital library which includes a category tag cloud so that you can choose terms such as "labor", "business and industry" or "social politics".
The Archives Service Center cautions on its website that some collections may be restricted. "Researchers should contact firstname.lastname@example.org or telephone 412-244-7091 in advance of any visit to ensure availability of any collection in which they are interested," they write.