Among the more than 5,000 maps and 550 atlases in the collections are virtually every printed map relating to the present United States before 1820, either in original copy or photostat, and these holdings are supplemented by hundreds of unique manuscript maps and an equal number of photostats of manuscript maps from other repositories throughout the world. The Division also includes an exceptional collection of bibliographies, promotional and state survey maps of the nineteenth century, and county atlases of the 1870s and 1880s.
Every American map is catalogued, whether separate or bound into atlases or printed books.
The Library maintains an active program of acquisitions, and the rich resources of its collections are backed up by the outstanding holdings of the University of Michigan's Map Room, which includes not only older materials, but all of the United States survey maps not collected by the Clements. The Map Division has a distinguished tradition, not only because of the richness of its holdings in printed and manuscript maps, but also as one of the first map collections to be treated as a serious historical resource. The Division came into formal existence in 1931 as a result of acquisitions of outstanding map resources during the previous decade. Essentially a book collector before the Library opened in 1923, William L. Clements had acquired several notable atlases and some exceedingly rare maps bound into books relating to the period of American discovery and exploration. However it was the fortuitous purchase in 1923-24 of the entire 50,000 volume library of Henry Vignaud , an American expatriate scholar of the Discovery Period, which established the Clements as an outstanding cartographic repository.