"In these initial investigations, we found no evidence that I-502 enactment, on the whole, affected cannabis abuse treatment admissions. Further, within Washington State, we found no evidence that the amount of legal cannabis sales affected cannabis abuse treatment admissions.

"The bulk of outcome analyses in this report used the within-state approach to focus on identifying effects of the amount of legal cannabis sales. We found no evidence that the amount of legal cannabis sales affected youth substance use or attitudes about cannabis or drug-related criminal convictions.

"Compelling evidence in other states suggest racial disparities persist or have become worse after legalization and the opening of a licensed marijuana market, even while total marijuana-related criminal justice incidents have decreased.

"Preliminary look at racial disparities in select counties of Washington

"More schools and students are captured in the HYS [Washington Healthy Youth Survey] than MTF [Monitoring The Future Survey] (Table). The MTF included fewer low–socioeconomic status and nonwhite youth in the prelegalization vs postlegalization period.

"The number of juvenile marijuana arrests decreased 16%, from 3,168 in 2012 to 2,655 in 2017. The rate of juvenile marijuana arrests per 100,000 decreased from 583 in 2012 to 453 in 2017 (‐22%).

"The number of White juvenile arrests decreased from 2,146 in 2012 to 1,703 in 2017 (‐21%).

"The number of Hispanic juvenile arrests decreased from 767 in 2012 to 733 in 2017 (‐4%).

"The number of Black juvenile arrests decreased from 202 in 2012 to 172 in 2017 (‐15%)."

"Data on youth marijuana use was available from two sources. The Healthy Kids Colorado Survey (HKCS), with 47,146 high school and 6,704 middle school students responding in 2017, and the National Survey on Drug Use and Health (NSDUH), with about 512 respondents in 2015/16.

"The Colorado Department of Public Health and Environment (CDPHE) analyzed data from the
Colorado Hospital Administration (CHA) with these findings:

"The increase in law enforcement officers who are trained in recognizing drug use, from 129 in 2012 to 214 in 2018, can increase drug detection rates apart from any changes in driver behavior.

"Traffic safety data were obtained from a number of different sources. Please note that traffic safety data may be incomplete because law enforcement officers may determine that alcohol is impairing the driver, and therefore additional (time consuming and costly) drug testing may not be pursued.

"The total number of marijuana arrests decreased by 52% between 2012 and 2017, from 12,709 to 6,153. Marijuana possession arrests, which make up the majority of all marijuana arrests, were cut in half (‐54%). Marijuana sales arrests decreased by 17%. Arrests for marijuana production increased appreciably (+51%%). Marijuana arrests that were unspecified, meaning the specific reason for the arrest was not noted by law enforcement, went down by 45%.

Total US
According to the National Survey on Drug Use and Health (NSDUH), in 2008-2009, an estimated 13.37% of young people in the US aged 12 through 17 had used marijuana in the past year, falling to 12.29% in 2015-2016. The NSDUH also estimates that, in 2008-2009, an estimated 7.03% of young people in the US aged 12 through 17 had used marijuana in the past month, dropping to 6.75% in 2015-2016.