This has certainly been a year for marijuana "firsts." Since the year began, Cronos Group became the first pot stock to uplist from the over-the-counter exchanges to a more reputable exchange, the Nasdaq, and Vermont made history by becoming the first state to OK adult-use marijuana entirely through the legislative process.

Looking ahead to June, Canada aims to become the first developed country in the world to legalize recreational marijuana, and cannabinoid-based drug developer GW Pharmaceuticals may get Food and Drug Administration (FDA) approval for Epidiolex as a treatment for two rare types of childhood-onset epilepsy. If approval is granted, it would mark the first time a cannabis-derived drug has gained the FDA's favor.

Residents in these states will be voting on a marijuana initiative this year

Of course, history is nowhere near done being made this year. There are no shortage of states with initiatives aiming to legalize medical or recreational cannabis in the 2018 elections. Here are two states where residents will absolutely be voting on a cannabis initiative at some point this year.

Michigan

Though there are few certainties with legal cannabis, one state that's guaranteed to be voting on a marijuana initiative this November is Michigan. In late April, Michigan's State Board of Canvassers ruled that proponents of a recreational marijuana initiative collected enough signatures to get the measure on the Nov. 6 ballot. This is sort of a second go-round for Michigan, which collected more than enough signatures in 2016, but failed to turn them in within the allotted time to get a recreational pot measure on the ballot.

If approved, the possession and sale of up to 2.5 ounces of cannabis would be legal. The state would impose an excise tax of 10% on retail cannabis, which would go along with the state's 6% sales tax. The estimated $100 million in revenue expected to be collected, assuming approval, would primarily go toward education and the upkeep of state roads.

Oklahoma

Another state where residents are guaranteed to be voting on a marijuana initiative this year is Oklahoma. That's right, the generally Republican-leaning Oklahoma is voting on a medical marijuana initiative (known as SQ 788) on June 26. Like Michigan, signatures were collected in 2016, with the expectation that a medical cannabis initiative would make it onto the 2016 ballot. However, it took until 2017, with the aid of an Oklahoma Supreme Court ruling, to officially get the measure on the ballot.

If approved by voters, medical marijuana would become legal, albeit patients would be required to obtain a license and be prescribed cannabis by a board-certified physician. Though there are no specific ailments listed on SQ 788, medical cannabis license holders would be allowed to possess up to three ounces of medical marijuana on their person, as well as eight ounces at their residence. A proposed 7% tax would be levied on medical marijuana.

Residents may be voting on a cannabis initiative in these four states

Meanwhile, there are a handful of states where signatures are currently being collected and/or verified. Though not guaranteed to make the 2018 ballot, these states are looking to have a better than 50-50 shot of initiative inclusion.

Arizona

Seeing as how Arizona was the only state to unsuccessfully pass its recreational cannabis measure in 2016, it's no surprise that marijuana proponents are focused on spreading awareness and getting another adult-use pot measure on the ballot this year. After all, the previous measure failed to pass by a slim margin (48% yes vs. 52% no). Most of Arizona's ballot initiatives require signatures to be turned in by July for verification and inclusion on the November ballot. If I were a betting man, I'd say that a recreational cannabis measure is likely to wind up on Arizona's ballot this fall.

Utah

Another one of those states that'll make you do a double-take is Utah. Despite being quite conservative, Utah residents appear set to vote on a medical marijuana initiative this fall. Proponents of the initiative collected about 200,000 signatures by mid-April, which was well over the 113,143 required for ballot inclusion. However, opponents of the measure have filed petitions to block its inclusion on the November ballot.

If approved, patients with proper medical cards would be allowed to buy up to two ounces of unprocessed marijuana with no more than 10 grams of tetrahydrocannabinol (THC) or cannabidiol (CBD) once every two weeks (THC is the psychoactive component of cannabis that gets you high, while CBD is the non-psychoactive component known for its perceived medical benefits).

Missouri

Like Utah, Missouri appears to be on the cusp of adding a medical marijuana measure to its November ballot. In early May, Find the Cures reported filing approximately 300,000 signatures, which is almost double the 160,199 signatures necessary to be validated for inclusion. Such a measure, if approved, would require a change to Missouri's constitution, as well as levy a 15% sales tax on marijuana at the retail level. Residents should know shortly if the measure will make it onto the ballot.

Nebraska

Finally, residents in Nebraska, a state with some of the most stringent cannabis laws in the U.S., could be voting on a pot initiative come November. The Nebraska Right to Cannabis Initiative would create an in-state constitutional right for persons over the age of 21 to possess, consume, manufacture, and distribute any species of plant that falls under the genus of "cannabis."

It would also make medical marijuana legal for persons under 21 with the permission of a guardian and the written recommendation of a healthcare provider. With signatures due by early July, it'll be a few months before we'll know whether it'll make it onto the ballot this fall.

It's going to be a busy election season for the legal marijuana industry.