The word "state" is used loosely in everyone's daily speech. It requires qualification for philosophy's purposes
Used loosely, it refers to any community of individuals who live peaceably with one another for their common good -- people who for the most part are not related in anyway by ties of blood or of consanguinity. In this sense of the word, the fifty states that are members of the American union are states, and so too is the United States of America.
However, the fifty states of the American union are not properly called states, because they do not have any external sovereignty; they cannot make war and peace with foreign communities; they cannot make alliances with them, or enter into treaties with them.
Philosophically, a state can be said to exist only when it is a community ruled by a person or persons who hold public office or offices that are defined by a constitution that the community has formulated and ratified. Another word for such a community, in which the rulers have no power vested in them personally, but only in the offices to which they have been elected or appointed, is a "republic." In this sense of the term, a community ruled by a king or despot is not a state.
Aristotle puts his finger on this point of difference between communities that are and communities that are not states in which the rulers are either elected or appointed officeholders. The citizens are those who rule and are ruled in turn -- rulers when they are public officials and ruled when they are returned to private life as citizens no longer in office.
In ancient Greece the city (or polis) was a state or republic. The word "citizen" derives its meaning from that fact.
Only a person who is governed constitutionally is properly called a citizen. If the constitutionally governed communities of Greek antiquity had been called "republics" instead of "city-states," the word "republican" could have been used instead of "citizen."
In the world today most of its population lives under dictatorships, not in republics. A very small percentage of the world's population lives in states that are clearly republics.