Studies show that legalized cannabis use on college campuses is rising and binge-alcohol drinking is falling.
Everyone knows that alcohol is almost as ubiquitous as books in college culture. However, according to two studies, cannabis consumption is now gaining on alcohol consumption in those states where it is legal. [1,2] And concurrently, binge alcohol drinking is dropping.
Overall Increase in Cannabis Usage Rates
Researchers at Oregon State University conducted a study in seven states where cannabis was legalized for adult consumption and 41 states where it was still illegal between 2008 and 2018.  Within those seven legal cannabis states, the study analyzed data from 135 colleges and data from 454 colleges from the prohibition states. The data was taken from the National College Health Assessment Survey results from 2008 through 2018.
They found that cannabis consumption increased in legal and non-legal states, but in legal states, the consumption increase consumption was significantly higher than in non-legal states.  Another study out of Oregon State University found that, in addition to increased cannabis consumption, the rates of binge drinking among legal-age students fell in jurisdictions where cannabis was legal. 
Between 2012 and 2018, six years with new and maturing legal markets, the numbers showed a steady increase in cannabis consumption in legal markets each year.  This is important because it demonstrates that these increases were not simply one-time spikes due to the novelty of legalization, but instead point to a continuing trend that has yet to drop or even level off.
Given the destructive nature of binge drinking, the drop in this activity in legal states is positive news. On its face, the drop seems likely attributable to the availability of legal cannabis and the increase in its use. However, more studies are required to determine whether it’s causative or simply a correlation.
- Bae, H., and Kerr, D.C.R. “Marijuana Use trends Among College Students in States With and Without Legalization of Recreational Use: Initial and Longer-Term Changes from 2008 to 2018.” Addiction [ahead of print], 2019, https://doi.org/10.1111/add.14939. Impact Factor: 6.851, Times Cited: 2
- Alley, Z., et al. “Trends in College Students’ Alcohol, Nicotine, Prescription Opioid and Other Drug Use After Recreational Marijuana Legalization: 2008-2018.” Addiction Behaviors, 102, no. 106212, 2020. Impact Factor: 2.963, Times Cited: 2