Now in its 249th year, this celebration of all things Irish attracts locals from across the area and tourists from across the globe.
"We've been to New York several times, but this was the sole reason we came, for St. Patrick's Day on this occasion," June O'Neill of Cork City, Ireland said.
"It's magical to hear the bagpipers. It's enchanting. It takes you to another place. It's very spiritual," Mary Cagney of Long Branch said.
Absolutely, says Irishman and Archbishop Timothy Dolan. This is his first St. Patrick's Day parade here in New York.
"We're celebrating the Feast Day of the Saints. A man who was head over heels in love with God and with Jesus Christ and with his church and wanted to bring that light and love and faith and hope to other people," Dolan said.
New York City Police Commissioner Ray Kelly served as the parade Grand Marshal. This year he and Mayor Michael Bloomberg enforced a strict 'no tolerance' approach to anyone showing up with alcohol.
"I do think it's a good idea because I've seen some drunk people along my travels to the parade route," Allison Kenny said.
Lastly, a sky of blue hung over the sea of green along Fifth Avenue -- a clear sign that on this day even Mother Nature is Irish.