HOBOKEN, N.J.  With its mile-long stretch of boutiques, restaurants and bars, this waterfront city long ago left its roots as a shipping and industrial center, finding new life as young professionals set up homes here, and hordes of younger folks arrive each weekend to drink.

There have been growing pains. Rent creeps toward Manhattan levels, and the nightlife scene can certainly get out of hand  especially around the city’s St. Patrick’s Day Parade, an event that has spawned so much rowdiness that the mayor is threatening to cancel it.

Those who favor banning the parade gained more ammunition after the festivities this year, which, by all accounts, got astonishingly out of hand soon after the parade ended on Saturday afternoon.

Indeed the level of excess is only now coming into focus; the city’s police chief and the mayor held a news conference on Tuesday to announce some of the grim statistics. There were 34 arrests, up from 25 in 2010. Two women told the authorities that they were sexually assaulted over the weekend.