Most modern thematic maps and atlases rely heavily on statistical data. The Geography and Map Division has several kinds of data resources in its collections with access to additional material available online. For example, recent census data can be found at the site for the U.S. Census Bureau External. Historical statistical data are also available. In the 19th century, three statistical atlases were produced to illustrate the results of the decennial censuses, all three of which are digitized and available.
The more recent census material is considerably more detailed. The Topologically Integrated Geographic Encoding and Referencing (TIGER) System, developed for the 1990 census and also used in 2000, provides a single, fully automated source from which data and cartographic products related to either census can be derived. While the Geography and Map Division holds extensive census material, including census tracts and all of the digital data stored in the TIGER files, the official Federal Depository for all census material is in the Serial and Government Publications Division.
Some of the publications based on this material, both in textual and cartographic formats, show rates of change between censuses over time. The Atlas of the 1990 Census by Mark T. Mattson contains population pyramids by age and sex for 1970, 1980, and 1989; for white, African American, and other races by age and sex for 1989; state populations by gender; births, abortions, and infant mortality by state; and the composition of households, including those with married couples and households headed by females.
Statistical data sets on CD-ROMs are sometimes published in conjunction with atlases. An example is the Dartmouth Atlas of Health Care, 1998, which shows the geographic distribution of health services throughout the United States, including information on mammography and breast-sparing surgery, based on information supplied by health care organizations and the U.S. Census. These kinds of publications allow users to incorporate the data sets into their own research projects.