Revelers at today's St. Patrick's Day Parade will see hundreds of familiar marchers, but they won't see the mayor or City Council, who are boycotting the event because it excludes LGBT groups. This is the first time in the parade's 252-year history that both the mayor and City Council as a body will not take part in the celebrations.

Gay rights activists say this move sends a major message.

"By gestures, city leaders can help us consider the meaning of cultural events," said Brendan Fey, who has organized his own St. Patrick's Day Parade in Queens that allows LGBT groups to march openly.

Aside from the council and LGBT groups, two beer companies -- Heineken and Guiness announced over the weekend they would drop their sponsorship of this year's parade. .

Although individual members can march on their own, the vast majority of council members said they would stand by City Council Speaker Melissa Mark-Viverito's boycott. The last mayor to not march in the parade -- for the same reason -- was David Dinkins in 1993. Other city agencies, such as the NYPD and FDNY, will participate.

City Councilman Danny Dromm, who is openly gay and a Catholic, said the parade's organizers are behind the times since attitudes toward LGBT groups have changed, even within the Vatican. He added that Dublin's St. Patrick's Day Parade changed its policies toward LGBT members,who can openly march.

"It may not be immediate but I think [the council's decision] pushes the issue to the forefront and applies presser to the organizers and increases the call for them to change," he said.

William Donohue, president of the Catholic League, however, felt that the council and mayor's decision ruins the spirit of the parade.

"That some want to deny Irish Catholics their constitutional rights, when no one is stopping them from having their own parade, is a sad commentary on the state of our culture," he wrote in an op-ed last week.

Former Mayor Michael Bloomberg, who supports LGBT equality measures, criticized Mayor Bill de Blasio's decision not to march contending that he needed to show support for the city's Irish community.

Councilman Jimmy Van Bramer, who is openly gay, disagreed and said fighting to change the policy will result in a St. Patrick's Day parade that is more enjoyable for all New Yorkers.

"The St. Patrick's Day Parade is a fun and opportune way to celebrate the Irish American culture. They may be the last ones to the party but eventually they will come around," he said of the LGBT policy.