ABSTRACT

Introduction The objective of this chapter is to provide a description of recent trends in rural land uses within the United States as the first step in developing an understanding of contemporary land-use issues. This discussion is placed in the context of recent policy discussions and hints at directions for future policy. Moreover, this description of recent trends provides a foundation for the subsequent assessments of the determinants and consequences of land-use change found in Chapters 6 through 12. This chapter focuses on changes in land use within the United States from 1945 to 1997. The period immediately following World War II is often considered the beginning of the mechanical revolution in agriculture and forestry. Over time, public investments in infrastructure such as roads and highways have continued to significantly impact the path of development and land-use change. We begin with an overview of measurement and data issues and a summary of the U.S. Department of Agriculture (USDA) data series, which serve as the basis of our historical assessment of rural land use. The discussion then turns to trends in land use, land ownership, and land quality. Measurement of Land Uses Before beginning our discussion of land-use trends, it is helpful to introduce terminology related to the measurement and description of land uses and land-use change. Terminology and data collection are important components of land-use research. A firm understanding of these concepts and measurement issues will improve interpretations of land-use data and policy recommendations. Two common ways of classifying land are by its use and by its cover. Land use is defined as arrangements, activities, and inputs people undertake in a certain land cover to produce, change, or maintain it (di Gregorio and Jansen 1997). Land cover is the observed biophysical cover on the earth’s surface. Use and cover classifications reference different aspects of lands and convey fundamentally

different information. However, it is important to recognize that land cover can affect human uses of the land and that human uses can change land cover. A second important consideration in reading this chapter relates to the landuse classification used by the federal government in the databases used/referenced here. Federal records may classify a single land area with a single land-use category, when in reality the land area has multiple uses. For example, some of the forestland managed by the U.S. Forest Service is also grazed, but this land is likely characterized as forestland in terms of use and cover. Multiple-use management of lands complicates the accounting of land uses. Land-use data are collected by a variety of government agencies for a number of purposes, and no single land-use survey covers all land in the United States. In addition, some government agencies collect similar data, but with differing concepts and definitions, resulting in different statistical estimates. An important example of this are the different estimates of urban areas as measured by the U.S. Bureau of the Census and the USDA. Land-use surveys generally vary in terms of statistical data collection methods and temporal and spatial scope. In order to provide a consistent and comprehensive understanding of land use, the USDA developed the Major Land Use Series. The Major Land Use Series is a data series of land use that is based on a variety of surveys and public administrative records of land use. In compiling the series, a significant amount of effort is devoted to reconciling the differences among the variety of data sources from which it draws, including the National Resources Inventory (NRI). In the discussion of changes in land use from 1945 to 1997, this chapter draws heavily on both the Major Land Use Series and the NRI. The land-use classifications and primary data resources of the Series and the NRI are described in the chapter appendix. Recent Land-Use Trends in the United States Data from the USDA’s Major Land Use Series (Table 2.1) and the National Resources Inventory (NRI) data series (Table 2.2) serve as the basis of this discussion. Table 2.1 presents the number of acres by land-use classification for select years between 1945 and 1997. Table 2.2 is an NRI-based land use transition matrix for the 1982-1997 period: the columns and rows of the table represent acres in each land-use in 1982, and 1997, respectively. Entries on the matrix diagonal indicate acres that did not change use over the observed time period, while entries on the off-diagonal indicate a transition (for example, 11 million acres of land classified as cropland in 1982 were classified as rangeland in 1997). The data presented in Table 2.1 provide a comprehensive picture of the land-use allocation over time, while the transition matrix in Table 2.2 helps to provide insight into the direction of shifts in rural land uses. The three major uses of land in the contiguous United States are grassland pasture and range, forestland, and cropland. In 1997, these three uses represented 84 per cent of all land in the 48 contiguous states. Their respective shares of the total land area have remained remarkably stable over more than five decades. The

share of land in cropland was 24 per cent in 1945 and 1997, with minor variation in the intervening years. The shares of land in forestland and grassland were only slightly less in 1997 than in 1945, 29 compared to 32 per cent and 31 compared to 35 per cent, respectively. These relatively small net changes at an aggregate level, however, mask the underlying dynamics of land-use change. The key point to note is where and when change occurs. With few exceptions (e.g., change to urban use), land-use shifts occur in both directions across land-use categories. For example, some land shifts from grassland to cropland during the same period that other cropland moves into grassland. Table 2.1 Major land uses of the contiguous United States, 1945-1997 (million acres)a, b

a Rounding may cause discrepancies between estimates of totals and summation of specific uses. b Total land area differs over time due to re-measurement of the U.S. land area. Sources: Major Land Use Series Data, Vesterby (2001).