Keep in mind, the 14th Amendment applied the bill of rights to the states, but that incorporation took time. So prior to the 20th century, and really prior to the 1930-1960s, states only had to follow their own constitution.

Which is to say, freedom of speech as we know it today-protection from all levels of government-was not a thing for most of American history.

So if the local police wanted to prevent you from flying a flag, they likely could.