The Data

Forest Products: Data were obtained directly from the USDA Forest Service. The data used in the graph for the entire United States are the same as those used in the Timber Harvest indicator. Because no data were available for 1980, the data were divided by the interpolated value for 1980. The same data are not available on a regional basis, so “removals of growing stock” was used instead. This statistic is defined as the net volume of growing-stock trees removed from the inventory during a specified year by harvesting, cultural operations such as timber stand improvement, or land clearing. “Growing stock” is a classification of timber inventory that includes live trees of commercial species meeting specified standards of quality or vigor. Cull trees are excluded. When associated with volume, it includes only trees measuring 5.0 inches (12.7 cm) in diameter or greater at breast height. In general, the trends in “total timber harvest” and “removals of growing stock” are similar. Again, these data were divided by the interpolated value for 1980 in each of the six regions. Data are included from all 50 states.

Marine Fish Landings: Data were obtained directly from the National Oceanographic and Atmospheric Administration (NOAA) and are described in the Fish and Shellfish Landings indicator. Data for Hawaiian waters were included in the Pacific Coast region and those for the Gulf of Mexico were reported in the Southeast region, even though a portion of these off the coast of Texas should be included in the Southwest region. Prior to 1976, much of what is now the Alaskan fishery—as well as portions of the other regional fisheries—was in international waters. These waters came under the control of the United States with the establishment of the U.S. Fishery Conservation Zone in 1976. Thus, the large rise in fish landings visible after 1976 (see the Commercial Fish and Shellfish Landings indicator) resulted from the acquisition of new territory rather than a jump in the productivity of a given area of ocean. It was possible to include this situation in the indicator in the Coasts and Oceans chapter (see the Commercial Fish and Shellfish Landings indicator); however, a similar approach was not possible for this indicator. For this reason, data prior to 1978 were not included. Landings were divided by the 1980 value, either nationally or regionally.

Freshwater Withdrawals: Data were derived from the U.S. Geological Survey Circular series Estimated Use of Water in the United States, which has been published every 5 years since 1950 (note: consistency issues prevented the use of data prior to 1960). More recent compilations (1985–2000) are available electronically at http://water.usgs.gov/watuse/ (see the technical note for Water Withdrawals, p. 254). Withdrawals for any given year (and region) were divided by the 1980 value.

Agricultural Products: Data are available online from the U.S. Department of Agriculture’s Economic Research Service (ERS). State-by-state data are from Table 7 of U.S. Agriculture, 1960–96: A Multilateral Comparison of Total Factor Productivity (Technical Bulletin 1895, available at http://www.ers.usda.gov/data/stateproductivity/). State data were summed for the entire U.S. graph. The data in Table 7 are normalized such that the output for Alabama in 1996 equals 1. These normalized data were summed, either for the nation as a whole or for each region, and then divided by the 1980 value to produce the index values for all other years. Note that the data series was reanalyzed by ERS, although differences between these new data and those presented in the 2002 Report are slight.

Human Population: Data are available online from the U.S. Census Bureau via the “national” and “state” links at http://eire.census.gov/popest/estimates.php. U.S. or summed regional data were divided by the value for 1980 to produce the index values for all other years. Note that data in the 2002 Report for 1991-1999 were based on post-censal estimates. These have been replaced by more accurate inter-censal estimates from the Census Bureau.

2003 Web Site Update: data were included for forest products, marine fish landings, agricultural products, and human population; data were not available for water withdrawals. Please see notes added under each subheading.

2005 Web Site Update: Data were included for human population (2003-2004, with slight revisions to 2000-2002 data), water withdrawals (2000), and marine fish landings (2003-2004). Updated data were not available for forest products or agricultural products.