Pew Research Center 1/22/2020

Drug arrests for cannabis is 40% of all drug arrests despite adult use legality in several states.

National Bureau OF Economics Research 3/2018

“However, these early reports of steep increases in (driving accients) are confounded by a number of factors. We contribute to this discussion by using a synthetic control method to compare the outcomes in Washington and Colorado to other states with similar pre-legalization economic and traffic trends. We find the synthetic control groups saw similar increases despite not legalizing marijuana. Moreover, the p-values suggest that the deviations Colorado and Washington did show from their synthetic counterparts are well with the range of deviations seen due to year to year variation.”