These companies are known to have large imagery libraries available. No endorsement is implied.
Fagatele Bay National Marine Sanctuary GIS Data Archive
This site hosts lots of data for American Samoa.
Pacific Islands Ocean Observing System (PacIOOS) Voyager
An interactive map interface for visualizing and downloading oceanographic observations, forecasts, and other geospatial data and information related to the marine environment and beyond. Primary geographic focus at PacIOOS is on Hawaiʻi and other U.S.-affiliated Pacific Islands throughout Polynesia and Micronesia: American Samoa,Commonwealth of the Northern Mariana Islands, Federated States of Micronesia , Guam, Hawaiʻi, Republic of the Marshall Islands, and Republic of Palau. U.S. Minor Outlying Islands are also included.
Provides access to "high-value" data of federal agencies.
GeoPlatform.gov acts a one-stop shop for geospatial data, with over 160,000 datasets registered in the Data Catalog
Download aerial photography, satellite imagery, elevation, and landcover datasets.
Tutorial: Finding Aerial Photography and Images using EarthExplorer (MIT Libraries)
Download orthoimagery, elevation, geographic names, hydrography, boundaries, transportation, structures, and land cover.
Tutorial: How to download data from the National Map Viewer (MIT Libraries)
GIS Data by State
Links to state data portals.
Australia Data and Applications (Australian Government/Geoscience Australia)
Japan (Harvard University)
China Data Center (Univ. of Michigan)
China Map (Harvard)
You must register in order to download maps or data.
LINZ Data Service (New Zealand)
Socioeconomic Data and Applications Center (SEDAC)
A broad variety of worldwide and country datasets.
Files provided on this site are created from OpenStreetMap map data. Because OpenStreetMap is a work in progress many of the countries are only partially mapped or are incomplete.
Esri Data and Maps
Publicly accessible layer files for use in ArcGIS. Searchable using box in upper right-hand corner of page.
Free crowd-sourced data. Download data package for a large-scale area. Other data packages downloadable at these sites:
Regularly-updated copies of the complete OpenStreetMap database
Regularly-updated extracts of continents, countries, and selected cities.
Extracts for major world cities and their surrounding areas
Downloadable tabular data for a broad range of indicators at the country level. Data are in various time series.
GIS Data Depot
Index to fee-based and free data at the country level as well as bundled data from the U.S. government ($). Search the site, including forums. Add 'data' to your search to limit search to data.
Selected GIS Data Repositories
Data may be licensed for local users only.
A dataset of country boundaries, incorporating changes in the period 1946-2012.
Global Administrative Areas (GADM)
Countries and lower level subdivisions such as provinces and departments.
ESRI Data & Maps for ArcGIS
A good source for administrative boundaries, countries, U.S. states and counties, and other vector data.
USDA Natural Resources Conservation Service
Soils, land use and land cover, NAIP imagery.
FEWS NET Data Portals
Famine Early Warning Systems Network (U.S. AID)
Africa, Central America, Caribbean, & Mexico; Middle East, South Asia, Central Asia.
US Forest Service Geodata Clearinghouse
Download data from Land Status Record System (LSRS) and 7.5' Forest Service topographic maps (pdf and geotiff). Includes state and private forestry assessment data.
Web mapping portal to real-time coastal observations and NOAA forecasts.
IPCC Data Distribution Centre (Intergovernmental Panel on Climate Change)
This site has climate, socio-economic and environmental data, both from the past and also in scenarios projected into the future. It is is designed primarily for climate change researchers--finding the data you are looking for may not be straightforward.
BISON (Biodiversity Information Serving Our Nation)
U.S. species occurrence data
Conservation databases. Includes socioeconomic data.
Land Cover Data links (Land Cover Institute)
Includes U.S. and worldwide data.
Interagency vegetation, fire, and fuel characteristicsmapping program. Data is at a 30 meter resolution and most appropriate for a landscape-scale.
Pacific Islands Benthic Habitat Mapping Center (UH Manoa SOEST)
Charged with mapping benthic habitat of coral reefs in the Pacific region on the U.S. and its Territories.
SocialExplorer (UHM login required)
Social Explorer provides quick and easy access to current and historical census data and demographic information. The easy-to-use web interface lets users create maps and reports to illustrate, analyze, and understand demography and social change.
World DataBank (World Bank)
Energy Maps and Data (U.S. Energy Information Administration)
International and country data are also available at this site.
National Historical Geographic Information System (NHGIS)
Free aggregate census data and GIS-compatible boundary files for the United States between 1790 and 2011.
Historical Census Browser (Univ. of Virginia Library)
Data drawn directly from historical volumes of the U.S. Census of Population and Housing.
Association of Religion Data Archive
A collection of surveys, polls, and other data submitted by researchers.
Soils -- NRCS Data Gateway
Start by selecting area of interest (on the right under Place Data Order). In the subsequent screen, scroll down to Soils to see data options. You will need to fill our a registration form to order data.
World Geologic Data (USGS)
In addition to many energy-related files, this site has extensive country-level feature datasets.