Yesterday, America took one step closer to a significant milestone in the history of medical marijuana: making states who prohibit medicinal cannabis a minority in the union.

On April 13, the Pennsylvania legislature approved a bill to legalize medical marijuana. It's now headed to the desk of Governor Tom Wolf. Given the governor's statement last night, the new law is pretty much a done deal.

"I am proud and excited to sign this bill that will provide long overdue medical relief to patients and families who could benefit from this treatment," said Governor Wolf.

This would make Pennsylvania the 24th state to legalize medical marijuana, bringing the nation within reach of making a profound statement: The majority of Americans not only support using cannabis for medical purposes, they're also prepared to legalize it.

Even though 81 percent of Americans approve of medical marijuana according to a 2015 Harris poll, it has taken a lot of time for state and federal governments to catch up with public opinion.

Many states poised to legalize medical marijuana

But that could change dramatically in 2016 as 12 more states could join that list, putting the states where medical marijuana is illegal in the minority. Other states considering bills similar to the one passed in Pennsylvania include Kentucky, South Carolina, Tennessee, West Virginia and Wisconsin.

And those are just the states pursuing legalization through legislatures. Many more are working on ballot initiatives head of the November 8 election.

Here's a list of states who have active ballot initiatives that would legalize medicinal marijuana this fall, according to Ballotpedia:

It might be overly optimistic to expect all 12 of these states will legalize either through state legislatures or ballot initiatives . But only two need to succeed in order to put the majority of states onside with medical marijuana. That symbolic victory would send a strong message to the federal government.

Right now, the outdated Controlled Substances Act (CSA) defines marijuana as a drug that has no medical value and is as dangerous as heroin. But if the majority of states recognize the medical value of cannabis, it would be harder for the DEA to justify the federal government's antiquated stance.

And it would likely give a boost to the larger legalization movement. So far, all the the legal states that have legalized recreational marijuana use began reforming their cannabis laws by approving medical marijuana. So getting the majority of states to accept cannabis as medicine could be an important step toward repealing federal prohibition.