“It’s a stunning collection,” said Ann D. Gordon, a retired professor at Rutgers University and the editor of the Elizabeth Cady Stanton and Susan B. Anthony Papers Project. “That it’s being delivered all in one piece, with such a clear provenance, is remarkable.”

The collection, which Ms. Gordon is so far the only outside scholar to see, includes 26 letters from Anthony, 10 from Stanton and dozens from other suffragists. There are also broadsides, pamphlets, newspaper clippings and other material that Hooker kept in a kind of circulating library, many with “I.B. Hooker, please return” marked in her handwriting.