GIS Data Sources: Starting Points

• ArcGIS Pro
• ArcMap Desktop
• ArcGIS Online
• QGIS
• R: Mapping and Geospatial
• Web Mapping
• Data and Visualization Sciences
• Introduction to Data Visualization
• U.S. Federal Government Publications
• U.S. Census
• ​Google Earth
• Maps

General

• ArcGIS Hub  Thousands of free GIS datasets primarily from U.S. federal, state, and local agencies, but some international areas, too.
• GeoPlatform.gov: Colllection of over 100,000 geospatial datasets in all sort of formats, from federal and state agencies, universities, non-profits, city governments, and other entities.
• ESRI Data & Maps Layers covering the USA, international areas, and the entire world (Duke Only) 

United States

• Census Bureau TIGER Data Products Includes the TIGER/Line Shapefile boundaries for Census geographies.
• Homeland Infrastructure Foundation-Level Data (HIFLD) An open data site from the Dept. of Homeland Security with a lot of GIS layers relating to infrastructure in the United States.
• The National Map From the US Geological Survey. A wide array of map data for download and online mapping products.
• USDA Geospatial Data Gateway US Dept. of Agriculture

International

• GADM Administrative boundaries of countries and within countries.
• UNEP Data Catalogue: Geospatial From the UN Environment Programme

Local Area

• NC OneMap North Carolina GIS data
• Durham County, NC, GIS layers (Duke Only) For newer layers, see Durham Open Data Portal.
• Durham Open Data Portal
• Duke GIS layers (Duke Only)

Data for History

• Euratlas Historical Political Boundaries of Europe (Duke Only)
• NHGIS US boundary files for 1790 through 2010