Photo: John Kees

Measuring America’s Disappearing West

A new project by the nonprofit Conservation Science Partners and the Center for American Progress finds that every two and a half minutes, a football field’s worth of open, natural area in the western United States disappears to human development.

Across the American West, some environmental changes are easier to grasp and measure than others. The Grand Canyon’s mile-deep rock layers tell us it is six million years old. A redwood’s two thousand rings date it to the Roman Empire. Yet, the extent to which humans have modified the western landscape can be stubbornly difficult to measure.

New roads, oil and gas wells, and houses spring up year after year, but how much land does this development now occupy? Which human activities are causing the greatest loss of natural lands, and where?

Without answers to these questions, it has been difficult to have an informed discussion about appropriate limits on human development in the West. Instead, for more than a century, Westerners have argued place-by-place over what to save and where to build.

Earlier generations flooded the Hetch Hetchy Valley to build a reservoir for San Francisco, but safeguarded Glacier National Park from mining. They conserved ancient sequoias in California’s Sierra Nevada Mountains, but cut much of the old growth in Oregon’s Coast Range.

Decisions about how to balance the extraction of natural resources with their protection test our values as much now as they did a century ago. Today, however, we can make these difficult choices with the benefit of rapidly improving information about the pace, scale, and impacts of natural area loss in the West.

In the coming weeks, we will release the results of a year-long project to measure and map the human modification of lands in the western U.S.* A team of scientists at Conservation Science Partners quantified human modification by leveraging nearly three dozen datasets and more than a decade of satellite imagery in an analysis of a dozen types of human activities for the 11 western-most states in the contiguous U.S.

Here are three of the project’s findings:

Human development in the West now covers nearly 165,000 square miles of land — that’s roughly the size of six million superstore parking lots.

It is an immense footprint, and it is growing fast. Each of the western states we studied lost hundreds of square miles of natural area between 2001 and 2011. Over the course of the decade, new human infrastructure in the West — including roads, mines, commercial and residential buildings, and logging operations — consumed an area bigger than Yellowstone National Park.

Source: Conservation Science Partners

Between 2001 and 2011, a football field’s worth of natural area in the West disappeared every two and a half minutes.

Increasing urban sprawl and energy development were the two largest drivers of natural area loss between 2001 and 2011. In Wyoming and Utah, for example, the footprint of oil, gas, wind, and other renewable energy projects grew by more than 38 percent in just 10 years. The land occupied by cities, suburban areas and other commercial and residential development grew by 17 percent across the region.

Habitat fragmentation is so severe that if you were to parachute at random into a natural area in the West, you would be, on average, only 3.5 miles from developed land.

Not only are roads, transmission lines, oil and gas wells, and housing occupying more land area, but development patterns are carving natural landscapes into smaller and smaller areas. This process, called fragmentation, severs natural movement corridors for wildlife and challenges management of public land resources, such as those that are facing ever-more widespread and intense wildfires.

The degree of human modification near the Bay Area and central California, 2011. Source: Conservation Science Partners

This analysis of human uses of lands in the West is only possible because of the availability and accessibility of an unprecedented volume of readily-available imagery and geographic data enabling a comprehensive analysis to reveal the condition and health of the West. We have far more to explore and understand, of course, and have already begun compiling and creating data to update the map of human modification to reflect conditions in 2016.

And while it is important that the scientific community continue to develop this information, it is just as vital that the public, planners, land managers, and elected leaders find ways to apply this emerging knowledge base to guide smarter development in the future. For example, these data and maps can provide the foundation for identifying and conserving a functioning network of large, intact, and connected natural lands, or for aligning local conservation actions with regional patterns of wildlife habitat that stretch across jurisdictional boundaries.

In our view, measuring a problem is a first step toward tackling it.

Conservation Science Partners and the Center for American Progress will release the full results of the Disappearing West project in the coming weeks, including interactive maps and data about natural area loss at the state and county level.

*Defined as the states of Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming.

David M. Theobald, Luke J. Zachmann, Brett G. Dickson, Miranda E. Gray, Vincent Landau, Christine M. Albano, and Dylan Harrison-Atlas are scientists with the nonprofit Conservation Science Partners. Matt Lee-Ashley and Nicole Gentile are with the Public Lands team at the Center for American Progress.

Learn more about Conservation Science Partners at and the Center for American Progress at