Legalized medical cannabis In the United States, there are 22 states that have already legalized medical cannabis. In those areas, different rules and regulations on the use, possess, and cultivation of cannabis is in place. Here is some useful information you might want to know when applying for a medical cannabis card: 1. Of the 22 US states, 20 of them require that an applicant provide a proof of residency in that particular state in order to be considered for a medical cannabis card. 2. ...