Soil Series Atlas

State soils and where series were established

50 of 52 state soils were first described in the state that chose them. Only 8 are the most extensive series in their state.

By Ethan Mitchell · Published · Data as of October 27, 2026

The atlas lists 52 state soils: one for each of the 50 states, plus Puerto Rico and the U.S. Virgin Islands. In 50 of the 52 cases the series was first described in the same state that later chose it, judging by the type location recorded in the Soil Classification database. The oldest state soils, Cecil and Windsor, were established in 1899; the newest, Threebear, in 2003. And a state soil is often not the most common soil in its state: only 8 of the 52 are.

Where the state soils were first described

Every series has a type location, the place of the pedon that defines it. For state soils the type location is nearly always inside the state. There are two exceptions. Narragansett, the state soil of Rhode Island, has its type location in Connecticut. Paxton, the state soil of Massachusetts, has its type location in Connecticut. Soil series do not stop at state lines, and a state can choose a soil that was first described next door.

Across all 90 atlas series, type locations fall in 50 different states and territories. Texas has the most, 7, followed by Nebraska with 6.

When the series were established

The year a series was established is recorded in its official description. The chart counts the atlas series by decade, with the state soils in red.

1890s: 2 series, 2 state soils218901900s: 10 series, 6 state soils101910s: 11 series, 5 state soils1119101920s: 13 series, 6 state soils131930s: 10 series, 5 state soils1019301940s: 9 series, 6 state soils91950s: 4 series, 3 state soils419501960s: 13 series, 6 state soils131970s: 14 series, 9 state soils1419701980s: 2 series, 2 state soils21990s: 1 series, 1 state soils119902000s: 1 series, 1 state soils1
Atlas series by decade established (all 90 series, light bars) and the 52 state soils among them (red). Hover a bar for its counts. Year from the official series description.

Most of these series are old. Of the 52 state soils, 30 were established before 1950; across all 90 atlas series the figure is 55. Only four were established in 1980 or later. The busiest decade for the whole atlas is the 1970s, with 14 series. The rankings page lists the fifteen oldest.

How state soils rank in their own state

Ranked by mapped acres inside their own state, eight state soils are the most extensive series there and 28 of 52 rank in the top ten. These are the 8 that come first:

StateState soilRank in stateAcres in state
FloridaMyakka1st of 4741,404,907
IllinoisDrummer1st of 5821,343,362
KansasHarney1st of 4523,873,178
MassachusettsPaxton1st of 196324,230
MichiganKalkaska1st of 6681,031,866
North DakotaWilliams1st of 3712,581,758
New JerseyDowner1st of 247254,841
PennsylvaniaHazleton1st of 4001,589,533

At the other end, these five state soils rank lowest among the series mapped in their own state:

StateState soilRank in stateAcres in state
VirginiaPamunkey197th of 70421,954
AlaskaTanana112th of 84397,235
IdahoThreebear112th of 1,80655,841
UtahMivida96th of 1,54160,750
ArkansasStuttgart47th of 359193,596

Rank depends partly on how long the list is. Idaho maps 1,806 series and Utah maps 1,541 series; even so, Threebear covers 55,841 acres of Idaho and Mivida covers 60,750 acres of Utah. In Alaska only part of the land has detailed soil survey data, which keeps every Alaska figure on the low side.

What share of the state they cover

Rank is one measure; share is another. Taking the acres of each state soil inside its own state as a share of all series acres mapped there, the median state soil covers 1.54% of its state’s mapped soil. The highest shares belong to Victory in the U.S. Virgin Islands (9.7%), Tunbridge in Vermont (8.3%), and Harney in Kansas (7.6%). The lowest are Pamunkey in Virginia (0.11%), Threebear in Idaho (0.20%), and Mivida in Utah (0.21%). A share of a few percent can still mean first place: in a state with hundreds of series, even the largest one covers only a small slice of the map.

The largest and smallest state soils

Nationally, the largest state soil is Cecil, the state soil of North Carolina, mapped on 5.49 million acres. Next come Williams (4.23 million acres) and Harney (3.89 million acres). The smallest is Victory, the state soil of the U.S. Virgin Islands, with 7,368 acres. By order, the state soils are Alfisols (11), Ultisols (10), Mollisols (8), Aridisols (5), Spodosols (5), Inceptisols (5), Andisols (3), Entisols (2), Oxisols (1), Vertisols (1), and Gelisols (1).

The state soils page maps all of them colored by order, and each state page ranks the largest series in that state. In the finder, tick “State soils only” to work with just these 52 series.

Sources

Data as of: Official Series Descriptions and Soil Classification database snapshot 2026-10-26; SSURGO tabular data as served by Soil Data Access on 2026-10-27 (survey area save dates 8/23/2026 7:48:35 PM to 10/26/2026 10:17:40 PM). Counts, ranks, medians and charts on this page were computed by Soil Series Atlas from those files. Data & method