The impact of marijuana legalization has been the subject of three recent university studies. Here's what they found:
-"Borders Up in Smoke" - The University of Nebraska at Omaha
Found that marijuana possession arrests have nearly tripled in seven counties that border Colorado. Sales arrests and other marijuana crimes like cultivation were flat.
"Without exception, the rate of marijuana-related arrests, jail admissions, and associated costs of incarceration have increased."
The university estimated the increase costs Nebraskans about $10.2 million annually.
But researchers warned that studying marijuana has limits.
"It is possible that the total costs incurred by the counties in our sample may be both under - as well as over - estimated. Moreover, in the absence of direct measures of actual marijuana use, possession, or sale (e.g., accurate self-reports), our analysis also relies on official measures of law enforcement and correctional activity."
- "Cross-Border Spillover Effects" - Washington State University
Found that counties bordering Colorado and Washington, which each legalized recreational marijuana in 2012, saw possession arrests jump by an average of 30 percent.
The study said recreational marijuana legalization "causes a sharp increase in marijuana possession arrests in border counties of neighboring states relative to non-border counties in these states."
Found that the issue is limited to adults, with juvenile possession rates staying flat despite recreational legalization in neighboring states.
It "has no impact on juvenile marijuana possession arrests but is rather fully concentrated among adults."
Also found that other marijuana crimes, including cultivation and marijuana sales were not impacted.
- "Drug Trafficking Under Partial Prohibition" - The University of Oregon
Found that nearly 12 percent of Washington State's recreational marijuana sales went to out-of-state consumers before Oregon legalized recreation sales in 2014.
"We estimate 11.9 percent of the marijuana sold in Washington was trafficked out of the state before Oregon legalized and 7.5 percent remains trafficked today."
After Oregon legalized, retailers in Washington border counties saw sales drop by an average of 41 percent with those nearest the state line seeing a 44 percent drop.
"Retailers along Washington's borders with Idaho and Canada experienced no such decline. The decline occurred equally across weekdays and weekends, and was largest among the largest transaction sizes, suggesting that drug trafficking, not drug tourism, was to blame."