Conducting a general search via Google can be a useful preliminary strategy to find out what institutions might hold materials relating to your research topic.
Try the following searches:
Limit your search to educational sites such as university libraries, archives, and special collections by including "site:.edu" with your search terms.
Adapted from Georgia State University Library.
If an author used an item from an archival collection in their research, it will appear in their footnotes or citations.
Some citations may only point you to the collection and the repository, while others may be more specific (e.g., "Lois Lilley Howe Sketchbook , M.F.A. April 10, 1883", 1883, cuid27813, Box: 27, Folder: 661. Records of Howe, Manning & Almy, Inc. and the papers of Lois Lilley Howe, Eleanor Manning O'Connor, and Mary Almy, MC-0009. Massachusetts Institute of Technology. Libraries. Department of Distinctive Collections).
Footnotes can be incredibly useful as a starting point when there is already material written about your topic. They can also point you to other materials and collections that you might not have known about otherwise.