Upon a quick scan of the U.S. Constitution, the only direct reference I find as to how state governments are to be structured is in article IV, section 4:
"The United States shall guarantee to every State in this Union a Republican Form of Government..."
Aside from this, there are numerous references to state governmental entities, but no explicit prescription for their structure, powers, or even existence (nowhere does it say "Each state shall have a legislature," for example). I'll list the ones I found below.
- Article I, Section 3.1: Legislature
- Article I, Section 3.2: Legislature, Executive
- Article II, Section 1.2: Legislature
- Article IV, Section 2.2: Executive authority
- Article IV, Section 3.1: Legislature
- Article IV, Section 4: Legislature, Executive
- Article V: Legislature
- Article VI, Section 2: Judges
- Article VI, Section 3: Members of legislature, executive and judicial officers
- Amendment VI: Jury of the state
What is meant by a "Republican Form of Government", and does a reference to a state governmental entity equal a requirement for its separate existence? Fundamentally, what are the hypothetical limits on a state government's structure?