Major Research Tools

National Historical Geographic Information System (NHGIS)

Data, Gateway

NHGIS is a data portal for U.S. Census data in both tabular and geospatial formats. It provides access to summary statistics and GIS boundary files for population and agricultural censuses and other nationwide surveys from 1790 through the present. Alternatively, for a user-friendly online mapping interface connected to this same data see Social Explorer.

Natural Earth

Data, Visual Resource

A source for free geospatial datasets covering the entire globe at small, large, and medium scales. Includes a variety of cultural and natural features as well as elevation and bathymetric basemaps.

PA Spatial Data Access (PASDA)

Data, Gateway, Visual Resource

PASDA is a portal for geospatial data from a variety of state government agencies. Use the Pennsylvania Atlas for a map interface for previewing and downloading GIS datasets. Use Imagery Navigator for access to aerial photography from 1996-present.

Social Explorer

Data, Gateway, Visual Resource

Online application for locating and mapping US Census data and other demographic resources. Maps created on Social Explorer can be exported as images. To download the data itself in tabular and GIS formats see National Historical Geographic Information System (NHGIS).

The National Map

Data, Gateway

The United States Geological Survey’s (USGS) geospatial data and maps website. Access to geospatial datasets for hydrography, elevation, wetlands and many other natural and cultural features. For an interactive map for finding data see the National Map Viewer.

U.S. Census Maps and GIS Data

Data, Gateway

Digital maps covering a variety of US Census demographic categories, plus GIS data in vector boundary files for spatial aggregations of tabular census data at all levels of the census hierarchy.

Other Suggested Research Tools

Atlas of Historical County Boundaries


"Presents in maps and text complete data about the creation and all subsequent changes (dated to the day) in the size, shape, and location of every county in the fifty United States and the District of Columbia." Available as interactive maps and shapefiles that can be downloaded for use with GIS software.

Bureau of Transportation Statistics Geospatial Portal


A comprehensive collection of geospatial data, apps and maps from the U.S. Department of Transportation. Use the National Transportation Atlas Database for access to geospatial datasets.

Center for International Earth Science Information Network

Data, Gateway

A center within Columbia University's Earth Institute, CIESIN provides an extensive gateway to data and other information focusing on human interactions in the environment.  Provides a topic search as well as subject access to spatial and tabular data sets held by CIESIN or hosted on its web site. 

Earth Explorer


USGS data portal for global remote sensing data from satellite and aerial photography.


From the EPA, map various types of environmental information, including air releases, drinking water, toxic releases, hazardous wastes, water discharge permits and Superfund sites. See also a broader set of Geospatial Resources from the EPA.

Environmental Dataset Gateway


U.S. Environmental Protection Agency (EPA) data catalog includes a wide variety of geospatial data.



Federated search platform for U.S. federal government geospatial data. Follow links to Apps & Services/Map Viewer for an interactive map interface for finding geospatial data.

New Jersey Geographic Open Data


Geospatial data portal for the New Jersey Office of GIS. A collection of state agency GIS data for the entire state.

New York State GIS Clearinghouse


New York state government’s geospatial data portal. Follow link to CUGIR, the Cornell University geospatial data repository for more state-wide datasets.


Visual Resource

A free, open source, editable map of the world. Users can choose various layers, add notes, and share or export the maps they create.

USDA Geospatial Data


A data portal which includes geospatial data created by various USDA agencies.

World Imagery


Using mapping application ArcGIS Online this web service provides satellite and aerial imagery for much of the world. Higher resolution imagery is available for the continental U.S. and parts of Europe. This imagery is not available for download but can be streamed to desktop GIS software for analysis or export.