The United States has a long and admirable history of protecting its natural heritage, from the creation of Yellowstone National Park in 1872 to President Obama’s February designation of the Browns Canyon National Monument in Colorado. Its national parks, marine protected areas, and natural reserves stretch from sea to shining sea. And yet many of the most biologically rich areas in the country remain unprotected. A study published this week in the Proceedings of the National Academy of Sciences shows that the largest swaths of protected wilderness in the Lower 48 are in the interior West. Meanwhile, the highest density of vulnerable species can be found in the Southeast, Texas, and California. “These priority areas are a relatively small part of the country,” says lead author Clinton N. Jenkins, founder of Biodiversity Mapping, a global GIS initiative that originated in North Carolina, and visiting professor at the Institute for Ecological Research in Brazil. “Pumping...