Soil off Route 66 in Oklahoma; photo by dotpolka on Flickr (noncommercial use permitted with attribution / no derivative works).
Official State Soil of Oklahoma
Oklahoma designated Port silt loam (Cumulic haplustolls) as the official state soil in 1987. All State Soils
Port soils are found in 33 of the 77 counties of Oklahoma and make up about 1 million acres. These soils are found on flood plains (subject to frequent, occasional, or rare flooding) in central and western Oklahoma.
Port silt loam is named after the small community of Port in Washita County, Oklahoma. Most of these acres are used as cropland to cultivate alfalfa, wheat, grain sorghum, and cotton. Some areas are used as pasture or rangeland.