Via the CDC: United States Geographic Distribution | Chikungunya virus. Click through for the full report and a map. The key points, with my bolding:
• Chikungunya is not a nationally notifiable disease in the United States. However, chikungunya cases can be reported to ArboNET, the national surveillance system for arthropod-borne diseases.
• From 2006‒2013, studies identified an average of 28 people per year in the United States with positive tests for recent chikungunya virus infection (Range 5‒65 per year). All were travelers visiting or returning to the United States from affected areas, mostly in Asia. Only a quarter of the cases were reported to ArboNET.
• Beginning in 2014, cases have been identified in travelers returning from the Caribbean. As of July 22, a total of 497 chikungunya cases have been reported to ArboNET from U.S. states and territories (Table). One hundred ninety-seven locally-transmitted cases have been reported from Florida, Puerto Rico, and the US Virgin Islands. All other cases occurred in travelers returning from affected areas in the Caribbean and South America (N=295), the Pacific Islands (N=4), or Asia (N=1).
• With the recent outbreaks in the Caribbean and the Pacific, the number of chikungunya cases among travelers visiting or returning to the United States from affected areas will likely increase. These imported cases could result in additional local spread of the virus in the continental United States.