Soil type by address

Quick facts

• How many US counties have mostly expansive clay? 287 of 3,122 rated counties have shrink-swell clay limiting slab homes on more than half their mapped land.
• How many have a high water table across most of their land? 1,061 of 3,122, rated for homes with basements.
• Do downtown addresses get a soil? Of the 11 public buildings we looked up on October 31, 2026, 9 sit on map units that are at least partly Urban land, 1 of them on Urban land alone. Urban land is buildings and pavement, not a soil.
• How fine is the map? A soil survey map unit covers several acres or more, so one lookup reads the neighborhood's soil, not a single lot.
• How current is it? The lookup asks USDA's Soil Data Access at the time you search, so it reads the survey version USDA serves that day, and the result names that version's date.

Examples

Public buildings in Texas, Ohio and Colorado metros, looked up on October 31, 2026. Shares are of the map unit at the building.

US counties by share of expansive clay

Each bar counts the counties whose mapped land falls in that band of shrink-swell clay (3,122 counties, USDA SSURGO August 5, 2026).

How the lookup works

Your browser sends the address to the Census Bureau's geocoder, which returns a point and a ZIP code. It then asks USDA's Soil Data Access which soil survey map unit holds that point and reads the map unit's soils (components) and their ratings. The address itself goes only to the Census geocoder (USDA gets the point), never to this site or its analytics, which see only the ZIP code's first three digits.

The shares use the same rules as our county and city pages: a soil counts as expansive clay when USDA's "Dwellings without basements" rating lists shrink-swell as a limit with a rating of 0.5 or more. A soil counts as a shallow water table when its "Dwellings with basements" rating lists a saturated zone the same way. Every soil in the map unit counts toward the total, including the ones USDA leaves unrated. Like the rest of the site, it reports a share of the map unit, not a water-table depth in feet. The county read below the soil comes from the address's ZIP code, as on the ZIP code lookup, with 33,354 ZIP code areas. Full method and sources.

The lookup does not cover Puerto Rico or other territories, and an address the geocoder can't match gets no result; try the ZIP code lookup instead.

Is this the same as Web Soil Survey?

It reads the same USDA soil survey that Web Soil Survey serves, at one point instead of an area you draw. Web Soil Survey gives many more ratings and reports for a drawn area; this page gives two of them, shrink-swell clay for slab homes and a shallow water table for basements, next to the county's drought and flood record. Foundation Soils vs Web Soil Survey.

Why does my address say Urban land?

Soil surveyors map ground under dense buildings and pavement as Urban land, not as a soil. Some surveys leave it unrated and some, such as Harris County's in Houston, rate it anyway; either way it isn't a reading of the ground. 9 of the 11 public buildings in the examples sit on map units that are at least partly Urban land. The table lists any other soils in the same map unit, and the county figures still apply.