The great social experiment that is marijuana legalization is now five years old, with six states already allowing legal marijuana sales, two more where legal sales will begin within months, and yet another that, along with the District of Columbia, has legalized personal possession and cultivation of the herb.

As a number of state legislatures—including Connecticut, Delaware, New Hampshire, New Jersey, New Mexico, and New York—seriously contemplate joining the parade this year, it's more important than ever to be able to assess just what impact marijuana legalization has had on those states that have led the way.

The prophets of doom warned of all manner of social ills that would arise if marijuana were legalized. From hordes of dope-addled youths aimlessly wandering the streets to red-eyed carnage on the highway, the divinations were dire.

And they were wrong. In a report released Tuesday, From Prohibition to Progress, the Drug Policy Alliance takes a long look at just what has happened in the states have legalized weed. It's looking pretty encouraging:

1. Marijuana arrests plummeted.

Well, of course. If there's one thing you could predict about legalizing marijuana, this is it. The decline in the number of pot arrests is dramatic: 98 percent in Washington, 96 percent in Oregon, 93 percent in Alaska, 81 percent in Colorado, 76 percent in D.C. That means tens of thousands of people not being cuffed, hauled away, and branded with lifelong criminal records, with all the consequences those bring.

The savings in human liberty and potential are inestimable, but the savings to state criminal justice and correctional systems are not: The report puts them at hundreds of millions of dollars.

2. But the racial disparities in marijuana arrests have not ended.

While marijuana legalization dramatically reduces the number of people arrested for marijuana offenses, it clearly does not end racially disparate policing. The vast disparities in marijuana arrests remain, even in legal states. Black and Latino people remain far more likely to be arrested for marijuana offenses than white people, despite similar rates of use and sales across racial groups. There is work to be done here.

3. A tide of teenage weed heads is not unleashed upon the nation.

High school kids in the earliest legalization states smoke pot at rates similar to kids in states that haven’t legalized it, and those rates have remained stable. In the later legalization states, rates of teen use vary widely, but have mostly stabilized or declined in the years leading up to legalization. And in those latest states—Maine, Massachusetts, Nevada, California—regulatory programs are either not yet in place or so new they're unlikely to have affected youth use rates.

4. The highways remain safe.

In the earliest legalization states, Colorado and Washington, the total number of arrests for driving under the influence of alcohol and other drugs is down, and the crash rates in both states are statistically similar to states that haven't legalized it. In fact, there seems to be no correlation between legalization and crash rates.

5. States with legal marijuana have lower rates of opioid-related harm.

In Colorado, an upward trend in overdoses began to decline after 2014, the first year of retail pot sales in the state. Other positive indicia come from medical marijuana states, which report a nearly 25 percent drop in overdose death rates, a 23 percent reduction in opioid addiction-related hospitalizations and a 15 percent reduction in opioid treatment admissions.

6. Marijuana tax revenues are big—and bigger than predicted.

Legalization states have collected more than a billion dollars in pot tax revenues—and that's not counting the monster market in California, where recreational sales just began this month. Likewise, slow roll-outs of taxed and regulated marijuana commerce in Maine and Massachusetts mean no tax dollars have yet been generated there. In the states that do have legal pot sales, overall sales and tax revenues quickly exceeded initial estimates.

7. Marijuana tax dollars are going for good things.

Like $230 million to the Colorado Department of Education in two years to fund school construction, early literacy, school health, and bullying prevention programs. Likewise, schools in Oregon get 40 percent of the pot taxes and schools in Nevada will get $56 million in wholesale pot tax revenues. Oregon also allocates 20 percent of pot taxes for alcohol and drug treatment, while Washington kicks in 25 percent. In Washington state, 55 percent of pot tax revenues fund basic health plans.

8. Legal marijuana is a job creation engine.

The legal marijuana industry has already created an estimated 200,000 full- and part-time jobs, and that's before California, Maine, and Massachusetts come online. As marijuana moves from the black market to legal markets, weed looks like a growth industry and job generator for years to come.

"Marijuana criminalization has been a massive waste of money and has unequally harmed black and Latino communities," said Jolene Forman, staff attorney at the Drug Policy Alliance and author of the report. "This report shows that marijuana legalization is working. States are effectively protecting public health and safety through comprehensive regulations. Now more states should build on the successes of marijuana legalization and advance policies to repair the racially disparate harms of the war on drugs."

In addition to reforming police practices to reduce racial disparities, the report also says there is more work to be done on fostering equity within the marijuana industry and points to models for doing so, such as the California provision that having a prior drug conviction can't be the sole basis for denying a marijuana license.

Having places where people can actually smoke legal marijuana also remains an issue, the report noted. Public consumption is not allowed in any of the legal states. It's a ticketable offense in some and a misdemeanor in others. Public use violations are also disproportionately enforced against people of color, and the imposition of fines could lead to jail time for poor people unable to pay for the crime of using a legal substance.

And what about the kids? The report notes that while legalization has generally resulted in reducing historically high numbers of young people being stopped and arrested for pot offenses, these reductions are inconsistent, and in some circumstances, young people now comprise a growing percentage of marijuana arrests. A model could be California, where kids under 18 can only be charged with civil infractions.

Legalizing marijuana may be necessary for achieving social justice goals, but it's not sufficient for achieving them. As this report makes clear, how we legalize marijuana matters, and that's still a work in progress. But so far, it's looking pretty good.