Marijuana legalization advocates in Ohio managed to get enough petition signatures to put the issue up for vote on the Nov. 3 ballot.

Secretary of State Jon Husted said Wednesday that the group ResponsibleOhio had gathered 320,267 valid signatures of registered voters, nearly 15,000 more than needed to place the marijuana legalization measure on the general-election ballot, the Associated Press reported.

The Marijuana Legalization Amendment would allow adults over the age of 21 to buy marijuana and grow up to four plants for personal use. It designates ten official growing locations to be set up around the state, which have already attracted private investors, and also creates a Marijuana Control Commission to regulate the growth, sale and taxation of cannabis.

Some marijuana legalization supporters have criticized the wording of the amendment, saying it would create a marijuana monopoly in the state. State lawmakers sent a separate anti-monopoly measure to the ballot in June to ask voters to ban monopolies and cartels. Officials said that the proposal is written to trump the marijuana measure and will take effect immediately since it's a legislative amendment, while the citizen amendment takes 30 days longer, according to Reuters.

Husted said that the language of the proposed amendment still needs to be approved by the Ohio Ballot Board, which is scheduled to meet on Aug. 18.

ResponsibleOhio spent more than $2 million on getting the petition out to voters, and investors have pledged to spend $20 million more in the 83 days until Nov. 3., in what USA Today says is the best-financed marijuana reform effort since the 1937 federal ban on marijuana. The effort will include a bus tour, door-to-door canvassing, Internet advertising, television and radio advertising and voter registration drives.

If the measure is successful, the Buckeye State will become the sixth jurisdiction to legalize marijuana, joining Colorado, Washington, Oregon, Alaska, and the District of Columbia. About half of U.S. states have legalized medical marijuana use.