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GIS: Open Source Data

QGIS - Open Source GIS Software

QGIS (Quantum GIS) is a free open source software that runs on Linux, Unix, Mac OSX, Windows and Android operating systems.

Getting Started & Tutorials:

Datasets: The Americas

The following data sources are freely available (with a few exceptions noted) meaning they can be accessed and used by anyone.

Datasets: The World

Datasets: United States

Notes about the U.S. Census

  • The U.S. Census uses it's own geography, which ignores local boundaries like neighborhoods
  • It does use official government boundaries like cities, counties and states.
  • City and Census Tract boundaries usually change with every decennial census.  Expect to see larger tracts for older census years
  • The U.S. Census is conducted every 10 years (decennial) and is mandated by the U.S. Constitution for the purposes of congressional apportionment.
  • Census data is based on a survey questionnaire so the questions asked (and therefore the available data) can change from census to census as questions are added and removed over time.  
  • To see what a specific Census asked, take a look at this Census Bureau publication which covers 1790-2000, and the Census 2010 questionnaire.
  • The Census Bureau now conducts the American Community Survey, an annual statistical sampling of households.  Data are reported in 1, 3 and 5 year increments.  
    • 1 year: Areas with population over 65,000 (most current data; smallest sample size)
    • 3 year: Areas with population over 20,000 (more reliable than 1 year; larger sample size than 1 year) [this series is being phased out by the Census Bureau]
    • 5 year: Covers all geographies, including very small areas (most reliable data, largest sample size)