NEW ORLEANS — New Orleans’ Carnival season is nearing its “Fat Tuesday” climax, with the last lavish Mardi Gras parades set to roll through historic neighborhoods while narrow streets of the old French Quarter host a raucous, continuous street party of revelers overflowing its bars and restaurants.

Two of the city’s favorite parades — the processions of Rex, King of Carnival and the Zulu Social Aid and Pleasure Club — were set to roll Tuesday morning on major thoroughfares. Monday night featured the parade of the Krewe of Orpheus, co-founded by home-grown musician and actor Harry Connick Jr. In addition to elaborate floats and marching bands, scheduled participants included Connick himself, actor Neil Patrick Harris and Harris’ husband, David Burtka.

New Orleans has the nation’s largest and best known Carnival celebration. It’s replete with cherished traditions beloved by locals. But it’s also a vital boost to the city’s tourist-driven economy — always evident in the French Quarter.

“No strangers down here,” visitor Renitta Haynes of Chattanooga, Tennessee, said as she watched costumed revelers on Bourbon Street over the weekend. “Everybody is very friendly and approachable. I love that.”

She and her friend Tiffany Collins wore giant purple, green and gold bead necklaces as they sipped drinks.

The annual pre-Lenten festivities aren’t limited to New Orleans. Similar celebrations are held in Louisiana and along the Gulf Coast. Mobile, Alabama, where six parades were scheduled Tuesday, lays claim to the nation’s oldest Mardi Gras celebration. And other lavish Carnival celebrations in Brazil and Europe are world renowned.

Monday’s activities in New Orleans also included an afternoon “Lundi Gras,” or Fat Monday celebration on the Mississippi Riverfront, including live music. Part of the event was the annual ceremonial meeting of the man tapped to be this year’s King of Carnival — chosen by the Rex Organization, a predominantly white group with roots in the 19th century — and the man elected king of the Zulu Social Aid and Pleasure Club, founded by Black laborers in the early 1900s. The meeting is a custom that began in 1999 in what was seen as a symbol of slowly eroding social and racial barriers.