Map of 2009 H1N1 Influenza Pandemic in US (IMAGE) University of Cambridge Caption The size of the dots is relative to city size, and the colors relate to the number of influenza cases, with green the lowest and purple the highest. Credit Julia Gog Usage Restrictions Please credit to Julia Gog License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.