BOSTON (AP) — A throng of revelers lined the streets of South Boston on Sunday for the city’s annual St. Patrick’s Day parade, one of the nation’s largest celebrations of Irish heritage.

The parade drew crowds from across Massachusetts and beyond, with marching bands, floats, veterans’ groups and local organizations making their way through South Boston.

Police lined the route as Irish dancers, bagpipers and Revolutionary War reenactors marched past cheering spectators. College students stood on rooftops and people leaned over porch railings to watch, many wearing green beads and Boston Celtics gear.

One student stood out in a fluffy green robe, while parents pushed toddlers in strollers draped with Irish flags.

The event is a major annual tradition in Boston, a city with deep Irish roots, and often coincides with celebrations of Evacuation Day, which commemorates the departure of British troops from Boston in 1776. Evacuation Day this year falls on Tuesday.

Preparations took weeks, as police, transit officials and emergency crews coordinated safety and transportation plans for the large crowds that packed the neighborhood.