For the first time in five years, Cinco de Mayo falls on a weekend. That's why DUI checkpoints and police patrols are increasing nationwide and task forces are setting up Friday night or even earlier. Other methods will also be used in certain cities where stationary checkpoints are impractical or not allowed. In San Francisco, for example, police will hop on motorcycles for mobile Cinco de Mayo DUI patrols around the city, the online SFAppeal reports. "We can ride right up to the driver's window and check for any signs of alcohol or drug impairment," a San Francisco traffic cop told SFAppeal. "There are a lot of motorcycles on the road, and you would be amazed at how many people do not notice us until they hear the sirens." DUI checkpoints reduce drunken-driving crashes by about 20%, according to the Centers for Disease Control and Prevention. Most DUI checkpoints - Cinco de Mayo checkpoints included - are conducted at night. That makes sense, as the rate of drunken-driving fatalities is about four times higher at night than during the day, according to the National Highway Traffic Safety Administration. Further, more than 30% of fatal crashes on weekends involve drunken drivers.