Every year, more than 1.35 million people are killed in car wrecks.

In an effort to bring those numbers down, some highway authorities are reminding drivers of the stakes. For a decade, nearly 900 digital signs on Texas highways have sent safety messages to drivers. Most of time, these signs convey a generic message, like “DON’T DRINK AND DRIVE.” For one week per month, they also include a morbid statistic: the number of deaths on Texas roads so far that year.

Most U.S. states have similar signs. A new analysis finds they may not have the intended effect. In a surprising paper published Thursday in the peer-reviewed journal Science, researchers find that signs communicating the number of on-the-road fatalities are associated with a slight increase in accidents — 1.35 percent — on stretches of highway downstream of the sign.