It's considered mandatory in all states to show up for jury duty and respond to the jury duty summons.
However some states do not force it as much as others and some states may even send a sheriff to your house to arrest you for not responding to the jury duty summons.
But then again some states do not worry about the Jury duty summons and do not have the resources or time to go after people who miss the Jury duty summons.
I've personally never responded to the jury duty summons I've gotten and never have had a warrant or been arrested over it.
But then again some people in other states have been arrested and had to serve 3 days in jail over missing the Jury duty summons.