>> reporter: they lit up in d.c. and san francisco and rocked in denver. but at this year's 4/20 celebrations, anxiety is also in the air after statements from the trump administration. homeland security secretary john kelly recently warned of a possible crackdown in states that have legalized pot. >> its use and possession is against federal law, and until the law is changed by the united states congress, we in d.h.s., along with the rest of the federal government, are sworn to uphold all the laws that are on the books. >> reporter: john hickenlooper is governor of colorado, the first state where legal recreational marijuana went on sale in 2014. do you think you or other states will go to court and fight this? >> well, we'll certainly explore every option. we should communicate and collaborate and not make a snap decision. >> reporter: in colorado, medical and recreational marijuana are now a $1.3 billion industry.