| Wetlands type | Mid-1950s | Mid-1970s | Mid-1980s | Mid-1990s |
| million acres | ||||
| Estuarine wetlands | 5.59 | 5.53 | 5.10 | 5.09 |
| Palustrine marshes | 33.07 | 24.31 | 25.88 | 25.01 |
| Palustrine shrub wetlands | 11.00 | 15.51 | 15.60 | 17.07 |
| Palustrine forested wetlands | 55.09 | 55.15 | 50.39 | 47.93 |
| Other palustrine wetlands | 2.70 | 5.35 | 5.14 | 5.79 |
| Total wetland acreage | 107.45 | 105.85 | 102.12 | 100.91 |
Sources: Dahl, T.E., R.D. Young and M.C. Caldwell, Status and Trends of Wetlands in the Conterminous United States, 1980s to 1990s (U.S. Department of the Interior, Fish and Wildlife Service, Washington, DC, Draft).
Dahl, T.E. and C.E. Johnson, Status and Trends of Wetlands in the Conterminous United States, 1970s to 1980s (U.S. Department of the Interior, Fish and Wildlife Service, Washington, DC, 1991).
Frayer, W.E., T.J. Monahan, D.C. Bowden and F.A. Graybill, Status and Trends of Wetlands and Deepwater Habitats in the Conterminous United States, 1950s to 1970s (Colorado State University, Fort Collins, CO, 1983).
Note: Totals may not agree with sum of components due to independent rounding.
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