STATEN ISLAND, N.Y. -- It's not exactly an armed insurrection, but the people of Staten Island, New York's smallest and most suburban borough, are threatening to go it alone.

After years of feeling ignored and exploited, they are talking about seceding from the City of New York. More than 85 percent favor cutting the 90-year-old cord that binds them to Manhattan, Brooklyn, Queens and the Bronx, according to a recent poll by the Staten Island Advance.

Given the legal hurdles involved, a City of Staten Island is probably destined to remain a local fantasy. But plenty of folks here are convinced that the island could manage its affairs far better than the city's sprawling bureaucracy does.

By Big Apple standards, the borough's 400,000 residents are a blip on the municipal radar screen, amounting to less than 6 percent of the city's population. But on its own, Staten Island would be America's 27th largest city; one with its own zoo, newspaper, college, children's museum, botanical gardens, beaches, hospitals, ferry service, 55 public schools and, beginning in 1989, a naval port with a battleship and 3,000 sailors.

A 25-member secession committee, named by Borough President Ralph J. Lamberti, reported in December that Staten Island's booming economy could sustain its $500 million level of government services and still have $17 million a year left over. A largely residential, middle-class haven, Staten Island is the only borough outside Manhattan that pumps more money into the city's treasury than it receives in services.

"We call ourselves the forgotten borough," says Paul E. Proske, chairman of Northfield Savings Bank and head of the secession panel. "We could be picked up and parachuted into Middle America and be very happy."

Talk of political independence intensified after a recent federal court ruling that may reduce Staten Island's voice on the city's powerful Board of Estimate. If the borough's influence is cut back to uphold the principle of equal representation, Lamberti says, "I see Staten Island being the new dumping ground for all the unwanted projects, all the not-in-my-back-yard problems."

Sitting in his office near the Staten Island Ferry terminal, where 21 million passengers a year take the half-hour ride to lower Manhattan, Lamberti says it is no coincidence that he presides over the world's largest garbage dump.

"People feel they're being asked to take all the garbage of the City of New York, that they're being asked to take a jail, to take homeless shelters, facilities for wayward youngsters," he says.

"We don't control our zoning. We don't control our land use. We could plan a heck of a lot better than the city plans for us and keep a more countrified setting."

Discovered by Giovanni da Verrazano in 1524, Staten Island was still a rural community of a few thousand when it voted to join Greater New York in 1898. The new metropolis was to consist of five boroughs, or counties, that would retain a strong voice in their affairs. But that concept eroded over time, and soon Staten Island, or Richmond County, could no longer fill its potholes without permission from City Hall.

With no physical connection to the city until the Verrazano Bridge to Brooklyn was completed in 1964, Staten Island remained a homeowner's oasis in an era of urban development and urban blight. It remains the only borough with no subways. Some neighborhoods still have no sewer service. And it is a Republican bastion in a city of Democratic one-party rule.

The opening of the bridge to Brooklyn triggered a housing boom that has nearly doubled the island's population. Les Trautmann, publisher of the Staten Island Advance, says that big-city problems led many affluent families to cross New York Bay in search of rolling hills and green grass.

"Most of our residents here are refugees from the other boroughs," Trautmann says. "We're still 90 percent white here. Most of the people here were fleeing from troubled areas. They want a place that's free from racial conflicts."

The population explosion has brought with it a host of familiar ills: sprawling town house developments, traffic-clogged roads and overcrowded schools. Trautmann blames a citywide zoning code "that's based on a Manhattan concept of what a city should look like, not on what a suburb in a city should look like."

Spurred by a slew of new corporate offices and shopping centers, Staten Island generated 3,000 new jobs last year, more than the combined total of Brooklyn, Queens and the Bronx. This kind of growth suggests that Staten Island easily could be self-sufficient.

Still, a municipal divorce would entail an endless list of property disputes. What would happen to the 970 New York City police officers, 828 firefighters, 128 garbage trucks and 27 salt spreaders now on Staten Island? What about city-owned property and pension obligations? Would Manhattan share the $20 million annual cost of the Staten Island Ferry?

These questions may be moot, for the secession panel concluded that Staten Island could not declare independence without a citywide referendum or an act of the state legislature. Lamberti thinks a legal case could be made that Staten Island can withdraw voluntarily from the 1898 compact. But, he says, "the reality is that the city ain't gonna let us go."

Proske, for one, is not ready to wave the white flag. He says an uprising for secession could attract strong support in Albany, particularly from upstate lawmakers who have little love for the city.

"I can see a slogan," he says. " 'How would you like to be part of the City of New York? We don't like it either.' "