Saint Patrick's Day is one of the world's most recognizable holidays, bringing to mind parades, green beer, and decorations featuring shamrocks and leprechauns. But behind these familiar traditions lies a history that is anything but straightforward. When All the World Was Irish explores Saint Patrick's Day celebrations around the globe and throughout history as generations of Irish emigrants carried their national holiday to their new homes. From Boston to Buenos Aires to New York, Melbourne, Toronto, Bangkok, and beyond, Saint Patrick's Day festivities became a way for the Irish diaspora to remain connected to their homeland while embracing their new communities.  

In this lively account spanning four centuries and five continents, historian Cian T. McMahon reveals how a local Irish feast day became a global phenomenon. Along the way, he brings to life the people, celebrations, and communities that have given the holiday its enduring appeal. Vivid and expansive, When All the World Was Irish goes beyond the pints and parades to show how people, whether of Irish heritage or not, have made Saint Patrick’s Day their own. 

Cian T. McMahon is professor of history at the University of Nevada, Las Vegas.