National Historical Geographic Information System

The National Historical Geographic Information System (NHGIS) is the nation's most comprehensive source for statistical data, geographic data, and metadata describing spatial characteristics of the American population from 1790 to the present. With 265 billion data points, NHGIS is the largest publicly accessible social science database in the world and is used by thousands of researchers. This project will implement four major improvements to the infrastructure of NHGIS. NHGIS will create data tables for the 1790-1940 decennial censuses from a massive new individual-level database. The project will develop new GIS data identifying locations of incorporated places and MCDs for the 1790-1970 censuses. Census unit boundaries frequently change from one census to the next, making it difficult to analyze population changes over time and space. NHGIS will interpolate census statistics from 1980, 1990, and 2000 and the American Community Survey to produce estimates for 2010 census areas at several geographic levels, including census tracts, places, county subdivisions, and metropolitan areas. Finally, the project will sustain and expand NHGIS education and outreach efforts, offering individual user support and in-person workshops, online tutorials, and web-based community tools.

NHGIS democratizes access to the census, the fundamental source of data about the U.S. population. The proposed improvements will be used for academic research and also for social science training, journalism, policy research at the state and local levels, and private sector research. This infrastructure will allow thousands of investigators in disciplines from economics and ecology to environmental and health policy to address changes across the broad sweep of time at fine levels of spatial organization. NHGIS provides a unique laboratory for the spatial analysis of economic and social processes and offers the empirical foundation needed for developing and testing models of society. Creating new spatiotemporal data for the period 1790 through 1940 will open new opportunities to investigate profound social and economic transformations of American society, including industrialization, immigration, westward migration, and urbanization. Small-area census data are the primary source for investigating such critical issues as suburbanization, the decline and rebirth of central cities, residential segregation, immigrant settlement patterns, rural depopulation, agricultural consolidation, and population shifts from the rust belt to the Sunbelt. The improvements to NHGIS will allow researchers to apply new and powerful approaches to familiar problems by broadening the scope of local and regional analyses to explore variations across time and space simultaneously.