ABOUT 1946, Jackson Pollock moved to the Hamptons with his wife, Lee Krasner, and started dripping paint. In the few remaining years before he crashed his Oldsmobile, he became rich and famous, and Abstract Expressionism became the battle cry of American art.

On the East End of Long Island, the tale of Pollock and Krasner, of sex, booze and art, is hot, and all kinds of movie people - Al Pacino and Robert De Niro included - have allegedly been snooping around the Hamptons. It was rumoured that Barbra Streisand looked at an estate where some of the action took place, a nice little summer place believed to be worth about dollars 22m. No, no, no, screamed the estate agent, Streisand was not looking, absolutely not.

Summertime in Hollywood-on-the- Atlantic, where Billy and Christie (Joel and Brinkley) hobnob with Spielberg and Streisand, and on Fridays the sky is as thick with private jets and helicopters as it was with birds in the Hitchcock film. 'There are so many helicopters,' says Janice Blackburn, a Londoner who summers in East Hampton, 'that it looks like Apocalypse Now.'

This is New York City's main summer colony, a collection of Long Island towns settled in the 17th century and loosely called the Hamptons. The East End, as it is known, shimmers with green fields and the sun is a big yellow pop art sun - naturally, for this is where a lot of artists came along with Pollock and Krasner, back when it was cheap.

There are gorgeous white-sand beaches, icy Atlantic water and a rich array of architecture: from period salt boxes in Sag Harbor to the turn-of- the-century mansions in Southampton and the bleached beach bungalows in Amagansett and East Hampton. There are pools, tennis courts and antique shops everywhere. Beautiful children cavort and sometimes show up with mummy at Bridgehampton's Candy Kitchen. They have plenty of savvy, these New York yougsters as they shoot the breeze about their social lives and horses. In the CashHamptons, as the writer Michael Thomas has called it, if there has been a recession it would be hard to tell, given the size of the parties, the frequency of the charity events and the opening of new eateries. At dusk on Saturday, traffic on the Montauk Highway, the only artery between the various Hamptons, slows to a crawl. The urgent concerns of summer are: will Jerry della Femina, whose East Hampton Point is the hot place to eat (although Sapore di Mare is still the best restaurant in East Hampton) ruin everything by putting up a shopping centre? Will Martha Stewart, America's doyenne of instant country living, smother everyone in a better class of ruffle?

In the ChicHamptons, the VW convertible seems to have replaced the Mercedes station wagon as the domestic car of choice, although I did see a full-blown Range Rover with black- and-white skin seats outside the Sagaponack General Store. The store is one of those 'down-home aw-shucks regular Garrison Keillor' sort of places. Except for the lobster salad at dollars 36 a pound and the St Tropez types, standing on the back of their espadrilles, the women wearing Spandex bandages, the men in embroidered velvet evening slippers, sans socks, the babies pulled in canopied little yellow trailers behind dollars 1,000 bicycles. Around here Calvin and Kelly Klein preside over the Hampton Classics, the big horse show at summer's end. Truman Capote lived in Sagaponack once. Simplicity in Sagaponack is simplicity in the same sense that Marie Antoinette was a milkmaid.

But flash and trash are nothing new on Long Island, where rum-runners got the booze in during Prohibition, in the jazz age. The original Long Island playground for the New York gentry was on the North Shore; it was known as the 'Gold Coast'. In the Great Gatsby, F Scott Fitzgerald wrote longingly of the green light at the end of Jay Gatsby's pier there.

For 19 months, from 1922 to 1924, Fitzgerald lived at 6 Gateway Drive on Great Neck Estates. Great Neck was 'West Egg', where Gatsby lived in the nouveau riche part of Gatsbyland. 'East Egg' was Sands Point, where the very rich lived, among them Gatsby's adored Daisy Buchanan and her husband, Tom.

But even the Hamptons and the Gold Coast together are only part of Long Island, this deposit of geological debris left behind, in bits, between 60,000 and 20,000 years ago by a glacier named Wisconsinan.

Stuck at a right angle to New York City, Long Island, all 1,700 square miles of it, is about 118 miles from Brooklyn to Montauk Point. Its westernmost end includes Brooklyn and Queens (although these are now officially part of New York City). About two-thirds of the way east, at Riverhead, it splits into two fins: the North Fork, with its potato fields and vineyards, and as rural as any place in America, and the South Fork where the Hamptons are.

Long Island is divided into two counties, Nassau and Suffolk, which tells you something about its Anglo- Dutch history. At its widest, it is only 20 miles across. The island has all the attributes of a little country: a population of about 10 million, its own railroad system, a vast network of highways and two of New York's three major airports (JFK and La Guardia). It has parks and universities, scientific facilities, baseball at Shea, tennis at the New York Open, racing at Belmont, and water sports everywhere.

Long Island's proximity to New York gives it a role as playground, bedroom, kitchen garden, fishery and cemetery (Walt Whitman is buried here; so are Teddy Roosevelt, Count Basie and millions of New Yorkers, along with Checkers, the Nixon first dog who resides at the Bide-a-Wee Pet Cemetery in Wantagh).

The island is an anomalous sort of place. Immortalised for its high life by Fitzgerald in the Twenties, its contemporary scandals run more to the crude suburban saga of Amy Fisher, the Long Island Lolita, and her paramour, Joey Buttafuoco, who inhabit an intensely suburban land.

The Dutch and the English fought over Long Island for decades. When the English grabbed most of the territory from the Dutch in 1664, New Amsterdam became New York and New Netherlands was renamed Yorkshire. Everywhere, especially the East End, is the detritus of Dutch and English colonialism: graveyards, churches, windmills, forts, silversmiths, barns.

A century later came the Revolution. The British occupation of Long Island, which lasted for seven years, was exploitative and cruel. The war ended with the Treaty of Paris in 1783.

The poet of Long Island's 19th century was Walt Whitman, who was born there in 1823, and wrote about it, calling it by its Indian name, Paumanok. In the early 19th century, Long Island had one big boom town: Sag Harbor. It was fantastically rich and cosmopolitan. When the whaling boom ended in 1850, Sag Harbor went into hibernation. Suspended in time, it remains a coherent little village, full of the loveliest period houses, especially the mansions on Main Street, with a whaling museum and original customs house. The American Hotel has the best food on the East End of Long Island, and Sag Harbor is relatively unknown. This is Provence before Peter Mayle.

By the 20th century, the gentry had discovered Long Island, and the westernmost towns were developing into suburbs, but it remained, by and large, insular, provincial and bigoted. In the Twenties, the Ku Klux Klan flourished; in the Thirties, on weekends, as many as 50,000 spectators came to see young men in jackboots and swastikas parade around Camp Siegfried.

If Walt Whitman was the poet of 19th-century Long Island, Robert Moses was the visionary of its 20th century. He was a public servant, master builder, manipulator, and monomaniac, and did more to change the face of Long Island, and New York, than any other person. He built the airports. He built the highways, public beaches and parks. He was appointed by Alfred E Smith, the legendary governor of New York State, and when the the gentry complained that if Moses succeeded, the area would be 'overrun with rabble from the city', Governor Smith replied: 'Rabble? That's me you're talking about.'

Then there was William K Levitt. Levittown was a ground-breaking idea - post-war tract housing that promised every American GI a home of his own, complete with washing machine, expandable attic and with easy payments. At the end of the war, on a potato field on Long Island, Levitt began building. He could build 35 homes a day - no union workers, no basements, appliances included.

Up went 17,447 houses (colour schemes were not optional). Levittown became synonymous with post- war suburbia, the optimism of affluence, the oppressive conformity that marked the all-American Fifties. In 1940, Long Island had a population of 600,000; by 1960 it was two million. To service its new residents, the island gave rise to another form of contemporary American culture: the mall.

Long Island's suburban charms are, increasingly, in its ethnic stew, as various as New York itself. Many of the offspring of immigrants who arrived at Ellis Island - Jews, Poles, Italians, Hispanics, Indians, West Indians - made their way to the 'burbs. As they arrive, the food gets better, the sports more various. This summer, the future came to Long Island as America's first official cricket ground opened. Newsday, Long Island's newspaper, tried valiantly to explain this arcane and weird new sport, reporting that it appeared to be attended by extremely polite behaviour on the part of the spectators, who said things such as 'well done, old chap' and ate curried chicken salad for lunch.

Still, for a visitor, it is coastal Long Island that has the most allure, a stunning corner of the world, with its delicious beaches, farm stands and fishing, swimming and boating. There are the Hamptons and, farther out, Montauk, which is raunchier and less fussy. There is discreet and old-fashioned Shelter Island, and Fire Island, a peculiar sand spit perched precariously between the Great South Bay and the Atlantic Ocean.

Thirty-five miles long and a couple of blocks wide, Fire Island has an astonishing assortment of communities - gay, funky, suburban, theatrical - and is the most magical of all Long Island sites because it has no cars. You go by ferry. All island transport is by foot or bike with a kiddie wagon to pull the groceries home.

Nowhere is the Great American Summer more iconically celebrated than in these Long Island beach towns. And there is no time better to visit them than in September when the summer people have mostly gone away.

Getting there from New York: the Long Island Expressway is the central artery. The Long Island Railway leaves from Penn Station. The Hamptons Jitney, actually just a bus that goes to all the Hamptons plus Montauk, costs about dollars 18 each way: it picks up at 41st Street and Second Avenue and takes two to three hours. Places to stay: 1776 House, East Hampton; the American Hotel, Sag Harbor; Ram's Head Inn, Shelter Island; Gurney's Inn and Spa, Montauk.

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