Method: The share of adults using cannabis in the last month is the figure reported by SAMHSA for the 18+ year old population in 2016-2017. That figure was then multiplied by the US Census Bureau's estimates of the 18+ population in each state for 2018 to calculate the number of adults regularly using cannabis. Finally, that figure was multiplied by $493 per user, which is the estimated amount of excise tax, state sales tax, and local sales tax raised in Washington State per regular user for the most recent 12 month period. In reality, the average regular user does not pay $493 in state and local tax in Washington because some unknown amount of tax revenue is raised from irregular users and from non-residents. Nonetheless, this approach can yield a reasonable revenue estimate in the face of data limitations surrounding these populations. Data from Colorado and elsewhere suggest that most tax revenue will come from frequent users who live inside the state's borders. Finally, it should be noted that while Washington State achieves this level of taxation through a 37 percent excise tax, 6.5 percent state sales tax, and 2.82 percent average local sales tax, a similar result could be achieved through an equivalently-sized tax based on the weight of cannabis, which is the tax structure recommended in this report. Indeed, achieving these revenue levels over the long-term, as cannabis prices fall, will likely require a weight-based tax.