National Wetlands Inventory
The National Wetlands Inventory Program has been producing wetland maps and geospatial wetland data for the United States since the mid-1970s. The focus of the program has been to map or prepare digital databases to deliver to the public, as well as project and report on national wetland trends using a probability-based sampling design.
The link address is: http://www.fws.gov/wetlands/index.html