medical insurance for travelers,I am US citizen?

Contact any agent or insurance company..If you want more guide means just take a look at the below link for free information about choosing the insurance plan.

Most health insurance companies require that you reside in the state that you are applying for coverage for at least six months out of the year. As for traveling, most reputable companies such as Blue Cross Blue Shield will cover you anywhere on the face of the earth for life threatening illnesses or injuries. Using their network of providers and hospitals throughout the U.S.A., and several hospitals abroad, will save you money as well. Look up your local Blue Cross in your state for a quote, and/or to apply.

I found interesting information about your answer travel ins here. http://all-insurance-online.blogspot.com/2007/08/specialty-insurance.htmlGood luck!