The St. Patrick's Day 2013 Event was the thirteenth content update to the game. The update was released on March 7, 2013 to all players, and featured two new characters, a new building, a new decoration, and a new site. The water in player's Springfields turned green for the event - a reference to the green dying of the Chicago River for St. Patrick's Day in real life.
This event was the first 'moderate sized' event, being followed by the 4th July 2013 Event about 3 months later. The 4th July 2013 Event was considerably larger than the St. Patrick's Day Event however. On St. Patrick's Day itself (March 17, 2013), a dialogue message was added and the player received five free Donuts from Homer.