Here's a link to the CDC report on Chikungunya, and the dispersal of the disease in the U.S. Currently, it has been found only in travelers, but it has been found in most of the continental U.S. At this time, there are no locally-transmitted cases reported here.
The Virgin Islands and Puerto Rico are a different story. There, locally-transmitted cases have occurred. In the US Virgin Islands there have been 2, and in Puerto Rico there have been 121. Chik hasn't yet hit Cuba or Jamaica, but almost all the smaller islands east are already showing local infections.
The CDC site updates their numbers every Tuesday. So if you're concerned about a particular outbreak of a disease, it's a good site to find current information at.
The CDC also maintains a traveler's site. So if you are planning to travel, you can check there for health updates and warnings about current outbreaks.