Here are some more little-known facts about St. Patrick's Day. The Irish began celebrating St. Patrick's Day as early as the ninth century. St. Patrick's Day was a minor feast day until Americans made it popular in the 1760s. St. Patrick's Day, particularly for Americans, is a day of drinking and debauchery. It is hoped that more people will learn about the origins of St. Patrick's Day and celebrate it with reverence and pride, so please share this article!