FILE - In this Sept. 18, 2012 file photo a caregiver picks out a marijuana bud for a patient at a marijuana dispensary in Denver. Pot smokers in Colorado were the biggest winners in the vote that legalized the drug. Now state regulators are working out the details of exactly how to tax it, so the benefits are shared statewide in the form of increased revenue. A state panel meets Thursday to draft final recommendations based on the voter-approved marijuana legalization question that asked for excise taxes up to 15 percent to fund school construction.(AP Photo/Ed Andrieski)

If voters in Oregon decide to legalize recreational marijuana this November, the state expects it could generate up to $40 million per year in tax revenue.

"The revenue estimate from taxes when fully implemented may range from $17 million to $40 million annually," the Oregon state financial estimate committee wrote last week. The committee is comprised of several high-ranking members of the Oregon state government including Secretary of State Kate Brown (D), State Treasurer Ted Wheeler (D) and the directors of the state's Department of Administrative Services and Department of Revenue.

The $40 million high end estimate is about $2 million more than previously projected by ECONorthwest in July, while the $17 million low end estimate is about $1 million more than previously forecast by the first draft of the Oregon committee's fiscal impact statement.

But estimates are just that -- and can prove to be difficult to determine in emerging marijuana markets. Colorado lawmakers originally projected about $134 million in taxes and fees generated from marijuana sales in the state, but later backed down from that by about $20 million.

Voters in three states and the District of Columbia will decide on new marijuana laws this November. Oregon and Alaska voters will decide on the full legalization of recreational marijuana, while D.C. voters will decide on an initiative limited to legalizing possession and home cultivation, excluding retail sales. Voters in Florida will decide on a medical marijuana ballot measure.