Tri-Co Resources
Haverford College Library and Special Collections
Swarthmore Special Collections
As a general rule of thumb, the Tri-Co libraries are all relatively small operations (though Swarthmore's libraries are larger than the other two) so it makes sense to contact a librarian at any location before visiting. Besides, you'll be visiting Special Collections at places that are bascially your home school, so the librarians will have more of a vested interest in your work than a random aid at a library downtown might.