Washington State Patrol troopers and other law enforcement agencies will conduct extra DUI patrols across the state this holiday season, one that started Dec. 15 and ends Jan. 1.

The extra patrols will target impaired drivers that are under the influence of alcohol and/or drugs.

Every December in Washington, at least 40 people die in traffic crashes, Sgt. James Prouty said.

There is an increase in the number of fatal crashes involving drivers under the influence, Prouty noted.

The greatest increase involves drivers with a combination of alcohol and drugs or a combination of drugs.

This number went from 78 fatalities in 2011 to 146 fatalities in 2015 — an increase of 68 fatalities in five years.