Lyft offers $4.20 off rides in Massachusetts on 4/20 in collaboration with NETA, Mass. Chiefs of Police Association

Ride-hailing service Lyft, in a collaboration with the Massachusetts Chiefs of Police Association and popular marijuana retailer New England Treatment Access, is offering discounts to riders across Massachusetts ahead of April 20, a day that has become associated with marijuana use.

The unofficial holiday reportedly dates back to the 1970s, when students from San Rafael High School in California met at 4:20 p.m. to smoke after school.

The April 20 date is annually celebrated even here in Massachusetts, with events such as the Extravaganja pro-marijuana festival that will take place in Northampton on Saturday. With a NETA retail marijuana business in Northampton and the increasing popularity of legal use, the event is expected to draw big crowds this year.

Northampton police expect traffic tie-ups from Extravaganja marijuana fest at Three County Fair

With one way in and out of the fairgrounds, police expect Route 9 will be backed up by traffic to and from the festival

In a promotion designed to prevent users from driving impaired, Lyft is offering customers the opportunity to get a $4.20 discount off of a trip with the “promo code” 420BOS19.

According to a Lyft spokesperson, the code will work on Lyft rides throughout Massachusetts on April 20. The company said its annual economic report found that in Boston, 63 percent of passengers are less likely to drive under the influence of drugs or alcohol due to the availability of rideshare services.

The promotion comes as Gov. Charlie Baker and other officials push for legislation to curb drugged driving, though experts say the state is “years away” from a conclusive marijuana test that can determine exactly when a person used the drug.

Gov. Charlie Baker pushes bill to crack down on marijuana-impaired drivers

The state's marijuana dispensaries have agreed to distribute postcards about the dangers of drugged driving to every marijuana customer.

“We’re thrilled to be collaborating with the Massachusetts Chiefs of Police Association and NETA as we work toward a similar goal and commitment, as well as provide Boston residents with a responsible and reliable ride option," Tyler George, regional director of Lyft New England, said in a statement.

Mark Leahy, the executive director of the Mass. Chiefs of Police, said the association urges residents to choose “a reliable option” to get where they need to go on April 20.

“We’re proud to work alongside Lyft and their commitment to safer and more connected cities," Leahy said in a statement.