USA has a federal system in which a person is a citizen of their specific state of residence, such as NJ or Cal, as well as a citizen of the US. State constitutions may grant certain rights above and beyond what are granted under the US Constitution and may impose their own obligations including the sovereign right of taxation and military service; each state maintains at least one military force subject to national militia transfer service, the state’s national guard, and some states maintain a second military force not subject to nationalization.
Citizenship in most cases relates to membership of the nation state, but the term can also apply at the subnational level. Subnational entities may impose requirements, of residency or otherwise, which permit citizens to participate in the political life of that entity, or to enjoy benefits provided by the government of that entity. But in such cases, those eligible are also sometimes seen as “citizens” of the relevant state, province, or region. An example of this is how the fundamental basis of Swiss citizenship is citizenship of an individual commune, from which follows citizenship of a canton and of the Confederation.