Recreational marijuana legalization is a major policy shift in the United States over the last 10 years, with more than 23 states (and Washington D.C.) having codified legalization either through ballot measure or legislation. As true whenever a consumer good changes from illegal to legal, this has had major ramifications for the criminal justice system, consumer culture, and markets. In this paper, I examine the effect that recreational legalization has had on the illegal market for marijuana in Oregon. I develop a municipality level measure on whether illegal drug markets were above the median and use that in a difference-in-difference analysis, pre- and post-legalization. I find that, post-legalization, municipalities where the illegal drug market was more rampant pre-legalization had less illegal marijuana activity post-legalization, controlling for municipality and year fixed effects. This suggests that the legal drug market could be crowding out the illegal market, and that the illegal market is not as robust as we have seen in other situations.