Grazing by domestic ruminant livestock is one of the most extensive land uses in the conterminous United States, with these grazing lands providing ecosystem services related to soil, water, air quality, and biodiversity, while serving as a major component of local communities and our food system. Despite its importance, national-scale data on the extent and distribution of livestock grazing are sparse due to the matrix of federal, state, Tribal and private management entities tasked with cataloging the spatial extent of grazing land ownership and management. Here, we compile a comprehensive geospatial dataset of federal, state, Tribal, and privately-owned grazing land at the county level in the conterminous United States based on data from state land boards, federal data portals, and the USDA National Agricultural Statistics Service. In this study, we estimate where grazing takes place at the county scale, rather than relying on land cover proxies (e.g., grassland, rangeland, pasture), as previous studies have done. Our analysis shows there are 2.8 million km 2 (1.1 million mi 2 ) of grazing land in the continental United States—36.5% of the nation’s total land—composed of 0.15 million km 2 (0.06 million mi 2 or 5.9%) state-owned grazing land, 0.94 million km 2 (0.36 million mi 2 or 33.6%) federal grazing land, 0.17 million km 2 (0.06 million mi 2 or 5.7%) Tribal land, and 1.53 million km 2 (0.59 million mi 2 or 54.6%) privately-owned grazing land. This is in the middle of the range of previous estimates—2.4 million km 2 (0.92 million mi 2 or 31% of land area) to 3.24 million km 2 (1.25 million mi 2 or 43%). We also assessed the relationship among grazing land distribution, ecological resilience, and residential development patterns. Our spatial analysis hints at positive correlations between grazing land and landscape resilience, indicating the importance of this land use for nature conservation, especially in the semiarid Mountain West, and in counties with a high proportion of federal grazing land. Our results show that most counties west of the Mississippi River primarily place new residential development on land that was previously used for grazing. Given high development pressures in counties with large proportions of grazing land, we see the resilience of these landscapes currently under threat. This dataset provides new insight on how grazing lands are distributed across the US, their ecological significance, and the risk they face from climate change and land-use conversion.
Bettigo et al. (Thu,) studied this question.