Note that the data published in the 2002 State of the Nation’s Ecosystems Report as well as the 2003 and 2005 Web-Only Updates have been superseded by the 2008 Report and thus should be used with caution. For the most recent data, purchase the 2008 Report from Island Press.

View Data for Change in Ecosystem Area

and between 900 million and 1 billion acres of grasslands and shrublands. Thus, each covered roughly half of the lower 48 states. While these estimates are necessarily imprecise, it is clear that croplands (including pastures) and urban and suburban areas—totaling together about 500 million acres—were created on lands that were either forests or grasslands and shrublands, causing the acreage of these ecosystems to drop. In addition, the area of freshwater wetlands has declined by about 50% since European settlement.

In reading these figures and the ones that follow, it is important to remember that the data presented here are from several sources; they do not add to 100% of the U.S. land area, and gains and losses cannot be tracked accurately from one system to another.

Coasts and Oceans include all waters in the U.S. Economic Exclusion Zone (EEZ), which extends 200 miles from the coastline. Because the area of the EEZ changes only when territory is acquired or international law changes, this indicator focuses on the dynamic area of mixed salt and fresh waters, or brackish waters, surrounding the U.S. coastline. Changes in the extent of brackish water reflect changes in the volume of freshwater runoff from the land, which can be altered by changes in climate and by modification of river flows by dams and other diversions. There are no current or historical data at a national scale on the area of brackish water. Another important aspect of the extent of coastal waters is the area covered by coastal wetlands, coral reefs, and shellfish and seagrass beds (see Coastal Living Habitats).

Croplands, that portion of farmlands that is actively used for crop production (including pastures), occupy about 24% of the land area of the lower 48 states, or about 455 million acres. About 23 million fewer acres are in active farmland use than in 1949, but over this period, farmland area has fluctuated. American Indians had some lands under cultivation before European settlement, but there are no firm estimates of this amount. Satellite-based methods produce an estimate of just over 500 million acres of croplands in 1992. This report also identifies a “farmland landscape,” which includes both croplands and intermingled and nearby forests, grasslands and shrublands, wetlands, and developed areas. One data source, included in the Annual Update 2003, showed a continuing decline in cropland acreage. See Cropland Extent.

Forests cover about 33% of the land area of the lower 48 states, or just under 620 million acres. When Alaska is added in, the total is about three-quarters of a billion acres, down from just over 1 billion acres before European settlement. In the lower 48 states, forested area has declined by about 6 million acres since 1955. However, there is more forest now than in the middle of the 19th century (not shown in the illustrations), when many parts of the country were cleared for agriculture and settlement (see the forest area indicator). Satellite-based methods produce an estimate of about 560 million acres of forest in the lower 48 states.