Archives generally collect the papers of individuals and organizations. They are not like libraries that collect published materials, such as books and magazines. Archives collect as much of the writings and media of people and organizations that donate to them as they can, and the papers are rarely very organized (think of your own computer files). Archivists impose some kind of order on the collections, generally by time, although there might be other organization levels, as well.
Just as archives collect different things than libraries, they also have different ways of showing researchers (you) what they have. Rather than searching a catalog that leads to a book, in archives, catalog searches generally lead to finding aids. Finding aids describe the collection; at a minimum, a finding aid tells you what is in the collection, how much of it there is (generally number of linear feet), and how it is organized (boxes and folders, digital files). Some finding aids have a lot of description and some are very scanty.
For this class, if you are not geographically close to a collection, consider carefully whether you have the time and resources to go to the collection and use it. Contact the archive before you go to make sure the material is ready for you to use it when you arrive.
The best research guide for finding collections local to you is the Research Guide for Finding Archival and Manuscript Collections.
Collections to Investigate Online
Here are some collections worth investigating. They cover labor, migrants/civil rights, or both. They are spread around the country, but most have some digital materials.
Cornell University, ILR School's Catherwood Library
The Kheel Center at the Catherwood Library: The Kheel Center for Labor-Management Documentation & Archives is the unit of Catherwood Library that collects, preserves, and makes accessible special collections pertaining to the history of the workplace and labor relations.
Labor Archives of Washington: There are links to digitized collections as well as physical only collections.
Digital Resource Guide for the Labor Archives of Washington: Created by the University of Washington: Pacific Northwest labor history. Use the topics to begin to explore our Digital Collections, and discover more about the history of workers and labor unions. Contains both digitized and non-digitized materials.
Oral History Portal: Covers more than labor; this a mix of race/culture/migration topics organized by digitization projects.
Seattle Civil Rights and History Project: A collection of collections about both topics, and their intersetions.
New York University Archives: The Tamiment Library & Robert F. Wagner Labor Archives: collections relating to labor and social history, the history of the Left, the place of workers in American society, and the evolution of labor law. It also holds significant collections relating to women's history, immigrant history, and other topics.
The digital collections are buried a bit deep, so I've surfaced the link to search them. Search results often do not show the term searched, so digging into the collections is necessary.
These are largely digitized photographs.
Labor History and Workplace Studies at University of Maryland
Searching for digital collections directly might necessitate searching in more than one box. The Labor Archives should be accessible by using the first search box. Very little of the collection has been digitized.
The Calisphere: A gateway to digital collections all over California. Contains images, sound, and text. Very rich and deep.
Register of the Survey of Race Relations: and interesting collection not included in the Callisphere. Includes some written accounts from immigrants.