State Soil Geographic Database (STATSGO)
State soil maps are made by generalizing the detailed soil survey data. The level of mapping is designed to be used for broad planning and management uses covering state, regional, and multi-state areas.  STATSGO data are available in the USGS Digital Line Graph (DLG-3) optional distribution format. NRCS soil map symbols are not normally carried within the DLG-3 file; however, these map symbols are made available as a unique ASCII file when NRCS soils data are distributed in the DLG-3 format. STATSGO data are also available in ArcInfo 7.0 coverage and GRASS 4.13 vector formats. see link at: http://www.nstl.gov/review/onepage/onepagst.htm

Soil Survey Geographic Database (SSURGO)
The most detailed level of soil mapping done by NRCS. SSURGO digitizing duplicates the
original soil survey maps. This level of mapping is designed for use by landowners, townships,
and county natural resource planning and management.

National Soil Geographic (NATSGO) Data Base
Digitizing is done by line segment (vector) format. The base map used is a 1970 Census Bureau state and county digital data base, Albers Equal Area projection.  Map unit composition for NATSGO was determined by sampling done as part of the 1982 National Resources Inventory (NRI). Sample data were expanded for these MLRAs, with sample design being statistically significant to state parts of the MLRAs.

NATSGO is linked to a Soil Interpretations Record (SIR) attribute data base through the NRI data base. The soil mapping units contain many components. Soil property or interpretative maps can be developed to reflect the percentage of the map unit having the queried properties or interpretations. For example, two soil informational or interpretational maps that can be made from the data bases are percentage of soils with less than 20 inches to bedrock and occurrence of hydric soils (from the NATSGO webpage).