The concept and definition of hydric soils, the soils found in wetlands, originated in 1979 and evolved over approximately a 20-year period as the needs for hydric soil changed from verifying wetland maps to placing boundaries around specific wetlands in the field. The term “hydric soil” was used for the first time in the wetlands classification system of Cowardin et al. (1979, p. 3) for the soils found in natural wetlands. The Cowardin classification system was developed to assist in the National Wetlands Inventory (NWI) of the U.S. Fish and Wildlife Service that was a national wetlands-mapping program. It defined wetlands as “…lands transitional between terrestrial and aquatic systems where the water table is usually at or near the surface or the land is covered by shallow water. For purposes of this classification wetlands must have one or more of the following three attributes: (1) at least periodically, the land supports predominantly hydrophytes, (2) the substrate is predominantly hydric soil, and (3) the substrate is nonsoil and is saturated with water or covered by shallow water at some time during the growing season of each year.”