A "green wave" refers to the programming of traffic lights to allow for continuous traffic flow (a series of green lights) over a number of intersections in one direction. In New York City, this “green wave” prioritizes bikers by timing traffic lights around the average biking speed, in addition to mitigating the negative effects of heavy automotive congestion. After a series of bicyclist deaths in 2019, the highest death toll for cyclists in two decades, the city decided to retime traffic lights, so that vehicles would have to travel an average of between consecutive green lights.