When Colorado legalized recreational marijuana sales, Denver embraced the opportunity with open arms.

The city is now home to more than 62 percent of all Colorado recreational marijuana retailers, who cashed in on $14 million in sales in January alone.

Other cities weren't so eager: heeding legalization opponents' safety concerns, several pushed off licensing retail sales. Some banned retail sales altogether.

"There will be many harmful consequences," Douglas County Sheriff David Weaver warned in a September 2012 statement. "Expect more crime, more kids using marijuana, and pot for sale everywhere."

"Thugs put on masks, they come to your house, they kick in your door. They point guns at you and say, 'Give me your marijuana, give me your money.'"

One California sheriff went on Denver television to warn that, as a result of marijuana in his county, "thugs put on masks, they come to your house, they kick in your door. They point guns at you and say, 'Give me your marijuana, give me your money.'"

Three months into its legalization experiment, Denver isn't seeing a widespread rise in crime. Violent and property crimes actually decreased slightly, and some cities are taking a second look at allowing marijuana sales.

"We had folks, kind of doomsayers, saying, 'Oh my gosh, we're going to have riots in the streets the day they open,'" Denver City Council President Mary Beth Susman, a supporter of legal marijuana, says. "But it was so quiet."

Denver's violent crime rate is holding steady

Denver's crime data shows a slight decrease in the past year: violent crime in January and February fell by 2.4 percent compared to the first two months of 2013.

Property crime is falling, too

Prior to legalization, opponents warned property crime would rise. Denver District Attorney Mitch Morrissey argued robbers would prey on marijuana businesses and their customers, because they're more likely to carry cash (and, of course, the drug).

So far, city data shows no increase in property crime. Compared to the first two months of 2013, property crime in January and February actually dropped by 12.1 percent. Reports of robberies and stolen property dropped by 6.2 percent and 13 percent, respectively. Burglaries and criminal mischief to property rose by only 0.5 percent.

Denver residents don't seem especially concerned with the issue, either. Susman recalls a recent community meeting she held with senior citizens: when she asked if the crowd wanted her to talk about marijuana, people told her they were tired of hearing about the issue.

"Based on my general understanding in my district, it is becoming ho-hum," Susman says.

Three months is still a short time frame

Some groups caution that it's too early to tell whether legalization will cause public safety issues in the long term.

"We quite frankly don't know," Smart Colorado spokesperson Henny Lasley says. Her group, formed after legalization, focuses on keeping marijuana away from children. "We've had three complete months of retail marijuana. We were getting those questions three days into legalization. It's a pretty short window."

Tom Gorman, director of Rocky Mountain High Intensity Drug Trafficking Area, thinks the full effects won't surface until, at best, three to four years.

"This is a great opportunity for us to find out what happens when you legalize a substance like marijuana," Gorman says. "Just wait and watch what happens in these labs, and then you can make a decision based on data and facts and not rhetoric."

Some marijuana legalization opponents, on the other hand, have adopted a softer opinion. Denver Mayor Michael Hancock, who opposed legalization, told CNN that the city's dive into recreational marijuana went smoothly. And despite some concerns about property crime, he said the city saw "nothing that has raised a major red flag."

Medical marijuana hasn't led to an increase in crime

Outside of Colorado, most research on crime and marijuana looks at legalization for medicinal purposes. One study published in PLOS ONE concluded the expansion of medical marijuana did not lead to more violent or property crime, and medical marijuana legalization might in fact correlate with a reduction in some crimes.

Researcher Robert Morris suggests that taking marijuana purchases out of an illicit market could reduce crime overall. "Perhaps there's additional crime associated with the criminal marketplace to begin with," he says.

Alternatively, crime could decrease if people began substituting alcohol with marijuana. "We know there's a pretty strong link between alcohol misuse and crime, particularly in a person of violence," Morris says. "There's not as much of a correlation between marijuana use and crimes."

Still, Morris cautions that the potential for crime reduction needs more study. He also says the findings don't necessarily apply to full marijuana legalization, and he would like to study that issue in further detail.

But concerns remain about businesses' cash holdings

If there's a reason for crime to increase following marijuana legalization, it may be the fine line marijuana businesses walk between legalization at the state level and criminality at the federal level.

Many banks decline to open accounts for marijuana sellers since the federal government still considers the drug illegal. As a result, many marijuana businesses hold raw cash — sometimes tens of thousands of dollars — from profits and to pay their bills. (The Obama administration, for its part, issued guidances telling prosecutors and regulators to prioritize issues other than marijuana in states where the drug is legal. But banks remain skeptical without changes in the law itself.)

Keeping cash on hand can be dangerous; a large stash of bills can be an easy target for crime. One study from researchers at the University of Missouri at St. Louis and Georgia State University found raw cash in welfare programs can lead to higher crime rates due to its liquidity and anonymity in transactions. Researchers found that Missouri counties that moved to electronic welfare benefits, from cash, saw crime drop by nearly 10 percent following the transition.

Denver District Attorney Morrissey says the amount of cash at marijuana businesses will near certainly lead to more crime. "You hit a 7-Eleven in Denver, you might get $20 to $100," he said in an interview. "You hit a dispensary on a good day, who knows? You might get $30,000 in cash."

City Council President Susman also worries the large amount of cash flowing in and out of these businesses could become an easy target for criminals.

"A grow operation will have a $20,000 or $30,000 utility bill a month," she says. "They have to show up at the utility's office with $20,000 or $30,000 in a briefcase."

Other Colorado cities are following Denver's lead

After Denver's smooth transition, other major cities in Colorado now appear ready to join. Aurora, the third most populous city in Colorado, plans to open recreational sales in October, even though medical sales remain illegal through voter rule. And Fort Collins, the fourth most populous city in the state, expects to have applications ready for recreational dispensaries in early April.

If Denver's experience holds true, the transition — at least for the first few months — should go smoothly.