Biologists have long known that large areas of roadless space are generally far more beneficial to the natural environment than multiple smaller areas broken up by roads. Roads lead to increased human activity, groundwater contamination, introduction of invasive species, and other environmental compromises. A new mathematical analysis, published in the May 4 Science, offers a visual model of the quantity and distribution of roadless areas in the United States, providing a clear and useful guide to the ecological value of land for scientists and policymakers.