The Archives of American Mathematics
The Archives of American Mathematics was founded in 1978 through a contract between the Mathematical Association of America and the University of Texas at Austin. It has become the de facto national repository for preserving the history of American mathematics.
A multi-year, EAF grant gave the Archives a strong start under the care of a full-time archivist. It contains the papers not only of the Mathematical Association of America and other institutions, but also of many individual mathematicians. It is housed in the Dolph Briscoe Center for American History at the University of Texas at Austin.
See also the Wikipedia article.