In a John Updike story, a preppy from Middlebury, Vt., refers to another from Greenwich, Conn., as a “city slicker.” Greenwich is in Fairfield County, but I suspect Mr. Updike’s Middlebury man would feel the same way about someone from Westchester County, in New York. These things are relative. We who live in the five boroughs regard Westchester people as anything but “city slickers.”

Westchester isn’t Mr. Updike’s turf, though. It was John Cheever’s. Cheever’s Westchester was a place of spiritual anomie. Many of Cheever’s stories were contemporaneous with – though very different from – “The Dick Van Dyke Show,” the bright cheerfulness of which was the perfect cultural projection of the optimistic values of the New Frontier. Rob and Laura Petrie, she (Mary Tyler Moore) in her chic capri pants, lived in New Rochelle, a town founded in the 17th century by Huguenot refugees who named it after La Rochelle, the stronghold of the Huguenots in France.

Cheever resided for many years in Ossining, home of the famous Sing Sing state prison, whose inmates once quarried the local marble that was barged down the Hudson to Manhattan in the mid-19th century. Westchester marble – from Ossining, Pleasantville, Eastchester, and other places – covers many great New York buildings, including St. Patrick’s Cathedral, La Grange Terrace on Lafayette Street, Federal Hall National Memorial, and the former New York Sun Building at Broadway and Chambers Street.

Sing Sing marble. John Cheever. Capri pants. Huguenot refugees. Maybe you’re getting the idea. Westchester is dazzlingly diverse, a point we city people seldom get. Therein lies the paradox of “The American Suburb,” the subtitle of the exhibition “Westchester” currently at the Hudson River Museum in Yonkers.The show is accompanied by a 504-page book, edited by co-curator Roger Panetta, with a collection of essays by noted scholars, including Kenneth Jackson and Frank Sanchis, the authority on Westchester architecture. There are also two related shows at museums in the country.

For the most part, it’s not going to be city people attending these shows. It will be Westchester people. It would, however, be good for city people to get on Metro-North to visit some of these shows, especially the one in Yonkers. What the city person may learn is that the histories of Westchester County and of New York City are closely intertwined – and not just by Metro-North.

In fact, part of Westchester County was once part of New York City. In 1874 the city, which was then just Manhattan, annexed the southern Westchester communities of Kingsbridge, Morrisania (the one-time estate of the princely Morrises, from Lewis to Gouverneur), and Twin Farms. In 1895, the city annexed further bits of lower Westchester. Not until 1914 did the borough of the Bronx cease to be part of Westchester County and become Bronx County.

Before getting all huffy about sprawl (as I in fact often do), it is good to remember that Manhattan itself developed exactly on the sprawl model many people deplore today. The first Dutch West India Company colonists settled at the southern tip of Manhattan Island, nearest to the harbor. As Manhattan’s population grew, it did so, quite naturally, in a northward direction, up the long, skinny island. By the 1820s the country village of Greenwich had been incorporated into the urban fabric. In the 1840s the large Murray farm was subdivided for development as a posh residential district.And so on. Soon enough, “upward and outward,” as urban sociologists say, meant not the Murray farm, but southern, and then northern, Westchester County.

At the northern border of the Bronx stretch, from west to east, the Westchester municipalities of Yonkers, Mount Vernon, and New Rochelle. They are in many ways typical of American cities’ inner-ring suburbs, in that they are old, and have experienced what we are inclined to describe as “urban” problems. And it is precisely to escape such problems that sprawl came to be, and persists. (In this regard I heartily recommend Robert Bruegmann’s recent book, “Sprawl: A Compact History” [University of Chicago Press].)

The Hudson River Museum show stresses the basic point that suburbia is not a phenomenon of postwar America and the GI Bill. It has long been a feature of American metropolitan life – as it was of English metropolitan life, whence many of our urban values derived. The show tells us of Washington Irving, who lived in his charming home, Sunnyside, in Tarrytown, and traveled to Manhattan to meet with publishers and friends. Irving’s lifestyle has some things in common with that of that other famous writer, Rob Petrie, as Rob commuted from New Rochelle to his Midtown Manhattan job as head writer on “The Alan Brady Show.”

All that said, it can’t be denied that after World War II suburbanization became a mass phenomenon on an altogether different scale. The historian John Lukacs is fond of pointing out that 1970 was a watershed year in American history, for in that year’s U.S. Census, for the first time in history a majority of a nation’s people lived neither in cities nor on farms, but in suburbs.When demographers speak of the “urbanized” parts of the country, they mean suburbs as well as central cities. Indeed, several of the municipalities within Westchester County are, officially, cities. And some, like White Plains, are nothing if not “urbanized,” by anyone’s standard.

Yet we all know there is a profound difference between urban and suburban, between Manhattan or Brooklyn and White Plains, let alone Bedford. But Murray Hill and Park Slope were once similarly, qualitatively, different from the denser parts of Manhattan or Brooklyn, and they in time came to be as much a part of the city as anyplace else.The difference between then and now is pretty obvious: the car.

When suburbanization began, there were no cars. Many Westchester municipalities developed around train stations. Some “railroad suburbs” remain among the most charming places in America. Others have eviscerated their downtowns, to baleful aesthetic effect, obviating any of the purported reasons for the suburb’s existence in the first place. In any case, it is hard to accept the thesis that people move to the suburbs today for the same reasons they did a century ago.

Back then, well-off people sought peace, quiet, cleanliness, and comeliness. Many suburbs today are seemingly endless snaking trails of automobiles and the vast infrastructure built to serve the motorized lifestyle – expressways and parking lots, shopping centers and strip malls and bigbox outlets. (The book to read here is Joel Garreau’s “Edge City: Life on the New Frontier,” from 1991.) Without placing a value judgment on this kind of suburbia, one may reasonably inquire whether the older form still exists, or can exist.

Some Westchester communities do care about conserving the old ways. In this regard, we may focus on the differing attitudes toward development of the city of White Plains, which is in lower Westchester, and the town of Bedford, which is in upper Westchester. White Plains, once a charming railroad suburb, has embraced the “edge city” ideal. It is a place of shopping centers and office buildings. Already the county seat of Westchester, it is now also the regional hub of business and commerce.

If White Plains has embraced hyper-development, Bedford, an affluent town, seeks to resist development to maintain its bucolic character. Reading through the 2002 Comprehensive Plan of the Town of Bedford (which can be accessed through www.bedfordny.info) is a fascinating experience. “The existing business districts in the hamlets of Katonah, Bedford Hills, and Bedford Village shall be walkable, [and] function efficiently and attractively within their existing boundaries….No new centers will be created. … Major research and executive office uses are not allowed.” Throughout, the plan refers to the major business centers of New York City and …White Plains.

Westchester is many things. It is Washington Irving and Rob Petrie. It is White Plains and Bedford. It is great that the people of Westchester can, through these exhibitions and their related programming, acquire a historical overview of their county. It would be equally valuable for city residents to get this suburban overview as well.