The graffiti block party on August 24th in Chelsea, which featured the painting of graffiti on nine imitation subway cars (life-sized but just two inches thick) by artists with names like T-Kid, Tats Crew, Min and Fuzz, was different from most street fairs in New York City in several ways. For one thing, a federal judge with a sense of humor had ordered it to go forward. The city had revoked its permit, after Mayor Michael Bloomberg had criticized the event for "encouraging people to hurt this city,” arguing that it would inspire people to deface real subway cars.

"By the same token, presumably,” Judge Jed Rakoff wrote in reversing the ban, “a street performance of 'Hamlet' would be tantamount to encouraging revenge murder."

It was also different because the entire block – 22nd Street between 10th and 11th Avenues -- was filmed by MTV and television news crews, and because both ends of the block had a big sign that said, “Warning: Anyone possessing spray paint, markers or other graffiti paraphernalia is subject to fine and arrest,” but that did not stop a crowd of young men in hip hop clothing, some wearing T-shirts that said “Graffiti Changed My Life,” from reverently lending their markers to the veteran graffiti artists for their autographs – excuse me, their tags.

But the graffiti block party was different, above all, because there was not a single sign-up table for a credit card, not one van with slabs of sweaty sausages on its mobile grill, not even tables full of underwear and socks for sale.

Block parties, street fairs, street festivals – there are a half dozen of them every summer weekend, there is at least one happening each week from May to November.The Saturday after the graffiti block party, which was organized by hip-hop clothing designer Marc Ecko, New Yorkers could attend:

• the Gramercy Park Neighborhood Festival, on Third Avenue from 14th to 23rd Streets
• Our Lady of Pompei Church Festival, on Bleecker Street from Sixth to Seventh Avenues
• the Federation of East Village Artists HOWL Festival on Tompkins Square Park and St. Marks Place from Avenue A to First Avenue

And then on Sunday:

• the Daytop Village Street Festival on Madison Avenue from 42nd to 57th Streets
• the Church of the Good Shepard/Third Avenue Merchandise Fair on Third Avenue from 23rd to 34th Streets
• Brighton Jubilee on Brighton Beach Avenue from Coney Island Avenue to Corbin Place, Brooklyn

If New York City’s first street festival was organized way back in 1884 on East 116th Street, by the Church of Our Lady of Mt. Carmel, the flowering of block fairs dates from the 1970s and 1980s, a result of the birth of neighborhood block associations in communities throughout the city.

So, if so many neighborhoods are so different, why are so many of the street fairs so exactly the same?

The reason for the monotony is simple. Many street fairs are managed by one organization, Mardi Gras Festival Productions.

Mardi Gras makes it easier both for the sponsoring organizations and for the vendors, by navigating what turns out to be a formidable permit process.

New York City street fairs are regulated by the Street Activity Permit Office of the Mayor’s Community Assistance Unit. The managers of any fair that takes place on more than one block or on more than one day must apply for approval to that office no later than December 31st of the previous year. Those block fairs that last only one day and take place only on one block can apply to the local community board. Manhattan’s Community Board 8, which includes the Upper East Side and Roosevelt Island, has recommended that the city approve 50 block parties this year in its area alone.

Mardi Gras helps the vendors obtain the necessary individual state and city permits they need. It also sells the vendors booths in the fairs it organizes -- and, if vendors buy a booth at more than one fair, they get a discount, which is why the same vendors appear in festival after festival. Mardi Gras also manages an aggressive corporate sponsorship program which is why you see the same oversized oddly-shaped plastic souvenir drinking glasses in festival after festival.

Many of the smaller block fairs are organized by neighborhood associations, and function as their main annual fundraiser, the money used to plant trees, fix lights and otherwise improve the quality of life in their communities. If they are enjoyable -- if they help the neighbors feel part of a community, and promote the neighborhood to the rest of the city -- so much the better. But their primary purpose is to make money.

The vendors are happy with this arrangement, the sponsoring organizations are happy, even the public is happy, judging by the crowds.

But not everybody is happy. The local merchants and residents along University Place in Greenwich Village were so sick of another identical fair week in and week out disrupting the normal street life that they circulated a petition against them.

And I am not happy that so many of the city’s street festivals have become nearly identical. I suppose it is wrong to denigrate Mardi Gras for doing to street fairs what developers and retailers have done to the rest of the city; after all, nobody is surprised to be able to board the 86th Street cross-town bus by the Banana Republic on Third Avenue and exit that bus by the Banana Republic on Broadway – or to cross a street to go from the Starbucks at 25 Astor Place to the Starbucks at 51 Astor Place, two of more than 150 identical Starbucks in Manhattan alone.

But there are plenty of street festivals that remain distinctive, some of them annual events. There are the grand spectacles, such as the lively Lunar New Year's Day parade in Chinatown , and the festival of the Giglio, in which 100 men carry an entire orchestra on their shoulders through the streets of Williamsburg.

And then there are the modest block parties, real neighborhood affairs managed not by Mardi Gras but by the neighborhood groups themselves. My wife and I reside in Yorkville, and one Saturday in June we attended a block party on East 87th Street to raise funds for the school at St. Joseph’s Parish. St. Joseph's has deep roots in Yorkville -– it started before the Civil War as a place of worship for an orphanage and became the church for Yorkville’s burgeoning German community in 1874 -– and this was evident in the June fair. A boy who attends St. Joseph’s school staffed a table selling used books. Another table functioned as a one-day “St. Joseph’s CafĂ©” –- full of goodies baked by the school’s parents or donated by local stores. There were children’s rides and a dunk tank. There was not one single place to purchase a tacky souvenir glass. It felt much better to attend a block party that was clearly a part of its neighborhood, and buy a book to support a neighborhood institution, than it would have to eat a sickening sausage at a roving shopping mall.

Marcus Banks is a librarian at the New York University School of Medicine.