NEW YORK » Crowds cheered and bagpipes bellowed as New York City’s annual St. Patrick’s Day parade kicked off today, and people with a fondness for anything Irish began a weekend of festivities from the Louisiana bayou to Dublin’s Parnell Square.

With the holiday itself falling on a Sunday, many celebrations were scheduled instead for today because of religious observances.

In New York, the massive parade, which predates the United States, was led by 750 members of the New York Army National Guard. The 1st Battalion of the 69th Infantry has been marching in the parade since 1851.

Michael Bloomberg took in his last St. Patrick’s Day parade as mayor, waving to a cheering crowd as snowflakes fell on Fifth Avenue.

Marching just behind him was Irish Prime Minister Enda Kenny, who presented Bloomberg with a historic Irish teapot earlier.

"The Irish are found in every borough, every corner of New York," Kenny said at a holiday breakfast. "In previous generations they came heartbroken and hungry, in search of new life, new hope; today they come in search of opportunity to work in finance, fashion, film."

Hundreds of thousands like the parade route in New York, cheering the marching bands, dance troupes and politicians.

"We’re crazy, the Irish, we’re funny and we talk to everyone," said 23-year-old Lauren Dawson, of Paramus, N.J., who came to her first St. Patrick’s Day parade.

In downtown Chicago, thousands lined the Chicago River and cheered as workers on a boat dumped dye into the water, turning it a bright fluorescent green for at least a few hours in an eye-catching local custom.

In a sea of people in green shirts, coats, winter hats, sunglasses and even wigs and beards, 29-year-old Ben May managed to stand out. The Elkhart, Ind., man wore a full leprechaun costume, complete with a tall green hat he had to hold onto in the wind.

"I’ve got a little Irish in me, so I’m supporting the cause," he said.

May bought the outfit online to wear to Notre Dame football games. But he figured it was fitting for this occasion too.

"I probably will get to drink for free," he said, after posing for a photograph with a group of women.

"That’s what I’m hoping," said his girlfriend, Angela Gibson.

Kenny, who visited Chicago for St. Patrick’s Day last year, was again making the holiday a jumping-off point for an extended trip to the U.S., with stops in Washington and on the West Coast over the ensuing several days.

"I will use my visit to promote Ireland’s many strengths and to further reinforce our deep and abiding political and economic relationship with the United States," Kenny said in a statement this week.

He and President Barack Obama were scheduled to meet at the White House on Tuesday and exchange shamrocks, a tradition that dates to Harry S. Truman’s administration. Obama also is slated to meet separately Tuesday with Peter Robinson, the leader of Northern Ireland’s Catholic-Protestant government.

Thousands of revelers gaudily garbed in green crammed the oak-shaded squares and sidewalks of downtown Savannah, Ga. today for a celebration that’s a 189-year-old tradition.

Led by bagpipers in green kilts, a parade kicked off this morning, hours after customers began lining up at downtown bars. More than 1,000 worshippers also packed the pews of the Cathedral of St. John the Baptist for the Mass that traditionally precedes the parade.

Bev Kehayes, of Greensboro, N.C., joined friends near the start of the parade route. She made hats with green feathers and flowers just for the occasion.

"It’s good, clean fun. Heaven forbid there’s a little alcohol involved," said Kehayes, who says she’s missed only three of the celebrations in Savannah in 29 years.

In Ireland, Dublin’s five-day St. Patrick’s Day festival was unfolding with a new addition. For the first time, up to 8,000 visitors from around the world were due to march in a so-called people’s parade on Sunday, when Ireland’s capital city also intends hold its usual procession of bands and pageantry.

In Maine, St. Patrick’s Day prompted Gov. Paul LePage to relent on a vow to veto any bill that reached his desk before lawmakers pass his proposal to pay a state debt to hospitals. He signed a measure Friday allowing bars to serve alcohol a few hours earlier than usual, starting at 6 a.m., on the Sunday holiday.

About 1,500 miles southwest, the city of Houma, La., was holding its unconventional celebration — an Irish-Italian parade, with a celebration that features both Irish cabbage and Italian sausage — on Sunday. The event resumed last year after a 10-year hiatus.

In Rolla, Mo., the Missouri University of Science and Technology continued a St. Patrick’s tradition that began in 1908, when students declared that the patron saint of Ireland also was the patron saint of engineers. A slate of events, which included a student portraying St. Patrick being transported downtown on a manure spreader, were to wrap up with a parade today.

Annapolis, Md., held its first St. Patrick’s Day parade March 10. A 40-year-old parade tradition took on a sense of renewal March 3 in Belmar, N.J., a shore town that took a heavy blow from Superstorm Sandy.

But along with the festivities, in some places, came warnings from police that they would be on the lookout for drunken drivers and other misbehavior.

New Jersey Transit officials said alcoholic beverages would be prohibited today on any train between Manhattan and Hoboken, N.J., a nightlife-friendly city across the Hudson River. Transit police arrested 16 people during St. Patrick’s Day last year, including two people who were charged with aggravated assault on two conductors.

In Baltimore, where last St. Patrick’s Day weekend was marred by a videotaped beating of a visiting man, fights and vandalism, police stepped up patrols and barred drinking in an area where revelers spilled out of bars last year.