Polio Timeline Polio Timeline http://amhistory.si.edu/polio/timeline/ Polio Timeline http://amhistory.si.edu/polio/timeline/ http://amhistory.si.edu/polio/timeline/ Polio History Smithsonian Institution Polio Timeline amhistory.si.edu/polio/timeline/ http://amhistory.si.edu/polio/timeline/ Smithsonian Institute - Polio Historical Timeline polio