www.washingtonpost.c om/news/post-nation/ wp/2015/01/23/how-th e-u-s-went-from
A study published in the Journal of the American Medical Association — Pediatrics last year found that 88 percent of measles cases in the country “were internationally imported or epidemiologically or virologically linked to importation.” There were a few cases not linked to any kind of importation over a period from 2001 to 2011, but they did not seem to be endemic, researchers said. The study ultimately found that while endemic measles was still eliminated, international importation remained a serious risk.
As long as people are traveling to and from other countries, and as long as some of these people may be unvaccinated and they may come into contact with other unvaccinated people, the risk remains of measles cases in the United States.