More than 20,000 people died on American roadways from January to June, the highest total for the first half of any year since 2006. U.S. road fatalities have risen by more than 10 percent over the past decade, even as they have fallen across most of the developed world. In the European Union, whose population is one-third larger than America's, traffic deaths dropped by 36 percent between 2010 and 2020, to 18,800. That downward trend is no accident: European regulators have pushed carmakers to build vehicles that are safer for pedestrians and cyclists, and governments regularly adjust road designs after a crash to reduce the likelihood of recurrence.