> If my memory is correct, Boston has banned masks.
California compelled the wearing of masks in post offices even after compulsory mask-wearing was discontinued at the federal level.
so... the question could be asked, who has jurisdiction in federal buildings such as post offices? or is jurisdiction a function of the particular legal domain to which a given law relates?
Logically it seems that if California allows a federal government facility like a post office, that it is compelled to allow federal law apply on the premises of that facility.