Citizens in the US have only one duty, to follow the laws of the federal, state, and local governments. We have the opportunity to vote, make public comment on any subject, to gather together, etc. That is established in the Constitution of the United States.
As to what happens if we don't do these things? If you break the law, you are tried and, if convicted, punished. If you don't vote or do any of the other freedoms granted by the Constitution, there is no legal consequence.
