Throngs of green-clad, shamrock-festooned revellers filled the streets of America’s most Irish big city on Sunday for the South Boston St Patrick’s Day parade.

Green, white and orange confetti – the national colours of the Emerald Isle – rained down along parts of the three-and-a-half-mile (5.6km) route. Parade floats and marchers wound through the neighbourhood of South Boston, a centre of Irish-American heritage in a city where more than one in every five people is of Irish descent.

Camryn Craddock was among those along the parade route.

“I just like the energy that everyone brings. Everyone’s really hyped up. It’s not boring,” the Massachusetts resident said. “I didn’t even really see much of the parade, but just seeing everyone having fun was really nice and everything.”

A drummer performs during the parade in Boston (Robert F Bukaty/AP)

Spectators packed behind metal barricades playfully hissed as colonial re-enactors wearing British tricorn hats and other period garb marched past.

The parade, which dates to the turn of the 20th century, marks both St Patrick’s Day and Evacuation Day, which commemorates the day in 1776 when British troops left Boston after a protracted siege during the Revolutionary War.

Parade-goer Alex Brough found people mostly behaved after violence and public intoxication marred last year’s festivities. Parade organisers moved up start of the festivities earlier and neighbourhood leaders warned of “zero tolerance” for rowdiness ahead of Sunday.

Before the parade, transit police posted a photo on social media showing a pile of clear rubbish bags filled with confiscated alcohol, including gallon-sized jugs filled with green liquid.Participants dressed as Minutemen march during the St Patrick’s Day parade (Robert F Bukaty/AP)

The South Boston Allied War Veterans Council organises the parade and this year’s chief marshal was retired Navy Lt Cmdr Alanna Devlin Ball, who represented the US at the 2023 Invictus Games in Germany where she took home gold in powerlifting.

The veterans’ council banned gay rights groups from marching in the parade up until a decade ago and a US Supreme Court ruling upheld that right in the 1990s.

Two gay and lesbian groups joined the parade in 2015. Organisers for one of the groups, Boston Pride, heralded the move as a point of progress at the time.

Chicago held its St Patrick’s Day parade on Saturday. Philadelphia also celebrated on Sunday and New York City holds its parade on Monday.