Thousands of San Francisco residents convicted of marijuana offenses since 1975 will see those convictions dismissed or reduced under an effort announced on Wednesday by the city's district attorney.

California's Proposition 64, which legalized recreational pot use and possession and reduced criminal penalties, allowed people to ask a court to reduce or dismiss past marijuana convictions.

But top San Francisco prosecutor George Gascon said on Wednesday he would not wait and would instead dismiss 3,038 misdemeanors and consider reducing an additional 4,900 felony marijuana charges.