The United States Department of Agriculture (USDA) Natural Resources Conversation Service (NRCS) has over a century’s worth of soil data that it actively collects and maintains. It creates a variety of products for farmers and soil scientists. There are two main data products of interest to GIS users: U.S. General Soil Map (STATSGO2) and Soil SURvey GeOgraphic (SSURGO) (and its related product gSSURGO.) STATSGO2 is a national product with a mapping scale of about 1:250,000 in the continental US and Hawai’i, and 1:1,000,000 in Alaska.
SSURGO data are the actual final soil survey datasets, with coverage for most of the country, at scales ranging from 1:12,000 to 1:63,630. Attribute details vary depending on the survey, but in general, more details are available when the survey was collected at a larger scale. Another feature of SSURGO is that the soils data and the soil mapping for the soil survey are separated. There is usually far more data from a soil survey than can conveniently be added to a single GIS dataset, so users pick the appropriate table from the database to join to the soil map using a key. gSSURGO is SSURGO data in an ESRI file geodatabase format, which can handle much larger datasets.