Soil Maps

Every map here reads the same USDA soil survey. Search a US address on any of them to see what the survey mapped at that spot, each map colored for a different property. Pick the map that answers your question.

• Soil type mapThe interactive map on the homepage: every USDA map unit, colored by soil type, for any US address.
• Soil pH MapTopsoil pH from acid to alkaline, and the states that run most acidic and alkaline.
• Soil Drainage MapNatural drainage from excessively to very poorly drained, and the wettest states.
• Prime Farmland MapUSDA prime farmland by address, and the share of each state that is prime.
• Soil Quality MapUSDA land capability by address, the standard rating of how suitable soil is for crops.

What each map shows

The soil type map colors each area by its main soil’s texture class, from sand to clay; texture is the mix of sand, silt and clay in the soil^[2].

The pH map uses USDA’s eleven reaction classes, from ultra acid (below 3.5) through neutral (6.6 to 7.3) to very strongly alkaline (above 9.0)^[3]. For a garden, that matters because most vegetables do best between pH 6 and 7^[4].

The drainage map shows the seven natural drainage classes, from excessively drained, where water leaves very rapidly, to very poorly drained, where free water sits at or near the surface for much of the growing season^[5]. In between, somewhat poorly drained soils stay wet at a shallow depth for significant periods of the growing season^[5].

The prime farmland map shows USDA’s farmland classes: prime, prime only once a condition is met (drained, irrigated or protected from flooding), and unique or statewide or local importance, the other farmland the Farmland Protection Policy Act names^[6][1].

The soil quality map shows land capability: eight classes by how much the soil limits field crops, where the first four can produce crops under good management. A letter after the class names the main limitation: e for erosion, w for excess water, s for the soil in the root zone and c for climate^[7].

How to read a soil map

Each colored shape is a map unit, an area the survey draws around one to three major soils^[1]. These maps color each unit by its main soil, so a small patch of a different soil inside it doesn’t get its own color. Tap or click a unit to see its name and the values behind the color; zoom in and the boundaries sharpen.

Reading a map unit’s name and legend

Tap a unit and you get its name as the survey gives it, such as ‘Clarion loam, Bemis moraine, 2 to 6 percent slopes’ in Story County, Iowa^[1], along with the class that sets its color. Each map’s legend lists its classes in order, so you can read a color without opening a unit, and areas the survey leaves without a value stay gray instead of taking a guessed color.

Four of the map pages also rank the states by the share of their soil in each class. They count only states with at least a million acres of rated soil, so a small state’s handful of acres can’t top a list, and every share comes from the same survey the map shows.

What the maps can and can’t tell you

The survey is made for planning by landowners, townships and counties^[1], so the maps are right for comparing places and seeing what to expect. They can’t tell you what sits under one spot in your yard, where fill, grading or a soil too small to map can differ. For a single lot, the soil tools read the ratings at your point, and a site investigation settles it.

Which map answers your question

Where the data comes from

SSURGO is published by USDA’s Natural Resources Conservation Service, built by walking over the land and analyzing samples in laboratories^[1]. The official database is refreshed once a year, with some updates in between^[8]. NRCS’s own viewer for it is Web Soil Survey^[9]; how the survey is made is on what is a soil survey.