Roaring traffic doesn’t stop big mammals like moose and bears from crossing highways—nor does it keep myriad smaller creatures from being squished by car tires. In just two years along one stretch of highway in Utah, 98 deer, three moose, two elk, multiple raccoons, and a cougar were killed in car collisions—a total of 106 animals. In the United States, there are 21 threatened and endangered species whose very survival is threatened by road mortalities, including Key deer in Florida, bighorn sheep in California, and red-bellied turtles in Alabama.

People are also hurt—about 200 die every year in the more than one million car collisions in the U.S., according to the National Highway Traffic Safety Administration. These crashes are expensive,