Soil Survey reports cover many counties of the United States, a report for each county, or for some large western states, portions of counties. These reports are available for request from the Southwest Regional Depository.
It is easy to find them in the Libraries Catalog. Do a Keyword Search, using soil survey, and a state name, like this: "Soil survey, Montana"
Or you can search for a particular county, using soil survey and county and state name, like this: "Soil survey, Butler County, Ohio"
Request them from a search result by clicking on the Available for Request link next to the location box.