Washington became one of the first states to legalize marijuana for recreational use in 2012. But there are a lot of challenges ahead: the state must set up a licensing system for marijuana growers and sellers, the federal government may mount a challenge, the need to set a new limit on amount of marijuana in the bloodstream for safe driving. And medical marijuana is still in the picture.Over the next several months we will be exploring the issue and tracking the impact of I-502.