Prime farmland and Hydric soil percentages were calculated by summarizing the component table associated with each soil map unit featured. Shapefile features are soil map units, and can only give a percentage of prime farmland or hydric soils occuring within them. The actual boundary of specific prime farmland or hydric soils is NOT shown in the features. Natural Resources Conservation Service, STATSGO metadata reports- "This data set is a digital general soil association map developed by the National Cooperative Soil Survey. It consists of a broad based inventory of soils and nonsoil areas that occur in a repeatable pattern on the landscape and that can be cartographically shown at the scale mapped. The soil maps for STATSGO are compiled by generalizing more detailed soil survey maps. Where more detailed soil survey maps are not available, data on geology, topography, vegetation, and climate are assembled, together with Land Remote Sensing Satellite (LANDSAT) images. Soils of like areas are studied, and the probable classification and extent of the soils are determined."