Focus on California – the search for free data

If you are looking for comprehensive and free data for a project, California hosts a wide range of federal, state and local agencies that readily make their data available at no cost. Many of these datasets can be easily downloaded from the Internet. Most can be found in common GIS and CAD formats such as ArcView Shapefiles, ArcInfo export (.e00) or Microstation (.dgn) files.

Administrative/Political

What’s a dataset collection without the most basic yet essential file of all? There are several sources to acquire boundary files depicting the boundaries for the state of California and its counties.

GIS Data Depot
Access datasets in ArcInfo format covering political, cultural and coastline free from the GIS Data Depot site.

Biological/Environmental

Environmental and biological are probably the most diverse and easily accessible free data categories in California. All sorts of comprehensive data ranging from wildlife species habitat, vegetation layers, national parks and more can be freely accessed from a variety of state and federal agencies online.

California Environmental Resources System
Bioregion data is available from the California Environmental Resources System agency. This web page is a clickable map linking to sites where you can download biological and environmental data for that region.

California Gap Analysis
Gap Analysis is a method by which protected areas are overlain with habitat ranges for endangered and threatened species. Sections of land are then identified where critical areas of habitat are unprotected, showing a gap. The University of California, Santa Barbara has made the California Gap Analysis data public. You can download data statewide or by region in ArcInfo format.

Land and Water

Geology
State Soil Geographic layer – a digital general soil association map developed by the National Cooperative Soil Survey.

Land Use
1:250,000-scale Land Use Land Cover for California. Also access 1:100,000-scale Land Use Land Cover for California.

National Hydrography Dataset
The National Hydrography Dataset (NHD) is a comprehensive set of digital spatial data that contains information about surface water features such as lakes, ponds, streams, rivers, springs and wells. You will need to click on California on the map to obtain the dataset for this state.

Topography
Free access to 1:250,000-scale Digital Elevation Models for California. Also access 1:100,000-scale Digital Line Graph for California.

Other Free Data Sources

There are a few sources out there that contain huge amounts of information that you can download spatial datasets for California from. One is the National Atlas. They have an interactive mapping viewer that allows you to browse and download datasets in ArcView shapefile format by state or by dataset type.

Another great resource is the GIS Data Depot. You can find all sorts of free datasets mostly derived from the USGS and other federal agencies.