When researching, it's important to think about collection items, collections, and archival repositories as part of a network. Each exists both individually, and as part of the larger historical record. Being aware of other collections and repositories can help provide broader context to your research. Archival research can sometimes be like making a collage - you have the autonomy to infer, interpret, and draw connections between documents and collections that might not be apparent upon first glance. You have the ability to piece together documents from different folders, boxes, collections, and repositories to develop your research narrative.
This page compiles together the special collections repositories at Yale, as well as some of the other major archival repositories beyond Yale. ArchiveGrid is also a helpful tool in finding additional collections across the United States.
For a complete list, please see: https://primarysources.yale.edu/explore-collections