The first official parade in the City was held in 1766 by Irishmen in a military unit recruited to serve in the American colonies. For the first few years of its existence, the parade was organized by military units until after the war of 1812. At that point in time, Irish fraternal and beneficial societies took over the duties of hosting and sponsoring the event.
Originally, Irish societies joined together at their respective meeting places and moved in a procession toward St. Patrick's Old Cathedral, St. James Church, or one of the many other Roman Catholic churches in the City. However, as the years passed, the size of the parade increased and around the year 1851, as individual societies merged under a single grand marshal, the size of the parade grew sharply.
Each year a unit of soldiers marches at the head of the parade; the Irish 165th Infantry (originally the 69th Regiment of the 1850's) has become the parade's primary escort, and they are followed by the various Irish societies of the city. Some of the other major sponsors and participants in the parade are the Ancient Order of Hibernians, the thirty Irish county societies, and various Emerald, Irish-language, and Irish nationalist societies.
Currently floats, automobiles, and exhibits, the usual elements that most people associate with parades, are not permitted in the parade, yet more than 150,000 marchers participate in the parade each year!