On April 19, 2019, the USCIS issued a policy guidance update in the USCIS Policy Manual. The update clarifies that violations of federal controlled substance law, including violations involving marijuana, are generally a bar to establishing good moral character for naturalization, even where that conduct would not be an offense under state law.
So, as you may know, several states have made marijuana legal for either medical or recreational use, and provisioned in those state laws is usually a stipulation that all dispensary customers are to give identification and be taken into a database. So if you purchased any marijuana from a legal dispensary, this could affect your ability to become a US citizen.
It is not clear whether or not these dispensary records are going to be shared between the states and the USCIS, and if and when we hear more about this, we’ll let you know. At this time, the only explicit means to them finding out about an alien’s legal marijuana use outlined by USCIS is by admission during an interview or arrest.
So, even though marijuana may be legal in your state, it is advised to avoid prior to naturalization, so it isn’t used against you to classify you as a person of immoral character.