No. Cannabis legalization has not increased cannabis use in adolescents. In fact, many studies have shown a decrease in adolescent use in association with cannabis legalization for medical or adult use.
As cannabis legalization has increased rates of adult cannabis use, it likely has increased rates of driving under the influence of cannabis. Presently, it is difficult to say by how much.
Despite 40 years of “gateway theory” scare tactics, there is little evidence to suggest that cannabis use increases the use of other drugs.
Based upon practical, neurophysiological, medical, and scientific considerations, there is a convincing rationale for limiting cannabis use to those 18 y/o or older. There is no support for limiting cannabis use to only those over 25 y/o.