This study tests the accuracy of disaggregating tourism time series by focusing upon the main regions of entry to the USA, using international arrivals data. Forecasts are run using the Basic Structural on monthly data. Accuracy of the arrival forecasts is measured for each region, and comparison is made of the forecast growth rates regional and nationally to compare the relative accuracy of different levels of aggregation. Forecasts of international arrivals are also made into the future for 2010-2015 for both the USA as a whole and for each of the main regions. These forecasts will provide interesting USA regional forecasts for the first time.