Are carbon monoxide detectors required in all States? It's just been mandatory in state of Florida?

Apparently it's mandatory since July 2007. But I wonder if anyone is really complying. How is it in other states, such as the ones up North where boilers are used? Regarding this law_even though there's seldom any boilers here_it is required because those are the ones more prompt to let lethal carbon monoxide out in case of accident!