According to Washington ProFile, Maryland became the second US state (the first was California) in which the governor approved such a bill. In six more states, the relevant legislative acts were passed by parliaments but did not receive governors' approval. In the late 1980s, the state of Alaska officially allowed the use of marijuana by anyone who wished. However, four years later the permission was rescinded because the state saw a sharp increase in the consumption of not only marijuana but also "hard" drugs (cocaine, heroin, etc.).
Interestingly, there is a legal paradox in the US: where marijuana is permitted for use, it is at the same time impossible to sell, buy, grow, or store it. These loopholes effectively leave marijuana consumption outside the law.