The study evaluates how well the EMAP-Wetlands sampling design estimates the wetland resource represented by the U.S. Fish and Wildlife Services's NWI digital wetlands data for portions of Illinois, Washington, and North and South Dakota. The EMAP-Wetlands sampling design was evaluated by comparing numbers of wetland polygons, total areas, and common versus rare classes in the EMAP sample to the NWI data base. Summary statistics demonstrate that the EMAP sample estimates compare well to the known population parameters, except for rare wetland classes. Rare EMAP classes, defined as comprising < 1 percent of the total number or total area of wetlands in a region, were estimated with poor accuracy and precision. Rare EMAP classes, in these regions, included saturated palustrine emergents, saturated emergents along rivers, and saturated forested/scrub-shrub wetlands along rivers.