BOOK REVIEW : Tales for the Rustication of City Dwellers : THE RIVERKEEPER <i> by Alec Wilkinson </i> Knopf $20, 191 pages

As originally conceived, The New Yorker was meant to epitomize urbanity in a literal as well as figurative sense. Named for the most urban place in America, the magazine was a Great Write Way of city style, a charmingly supercilious blend of sophistication and socialites, quips and cocktails.

That began to change after World War II. William Shawn’s succeeding Harold Ross as editor in 1952 accelerated the process, and some time in the ‘60s (perhaps with its serialization of Rachel Carson’s “Silent Spring”) or the early ‘70s (serializing “The Greening of America”) the rustication of The New Yorker became irreversible.

Oh, the magazine would always be a city dweller. It was just that Eustace Tilly now had a place in the country too--one where he was spending more than just weekends. It was somehow emblematic that such prized ornaments of The New Yorker as E. B. White, John Cheever and John Updike were ceasing to be New Yorkers.

Alec Wilkinson, who’s been a New Yorker staff writer for a decade, exemplifies this trend. He specializes in leisurely looks at out-of-the-way America. His first book, “Midnights,” recounted a year Wilkinson spent as a Cape Cod policeman. “Moonshine” memorably profiled a North Carolina revenue agent. And “Big Sugar,” examined the plight of cane-field workers in Florida.

His latest book, “The Riverkeeper,” comprises three similar items: a look at the annual blessing of the fishing fleet in Provincetown, Mass.; a profile of John Cronin, whom the Hudson River Fishermen’s Assn. employs to patrol that river; and the book’s longest piece, an extended visit to Angoon, “a shacky, tenacious, remote, defiant little frontier-speck of an Indian town on Admiralty Island in southeast Alaska.”

As the use of a word like shacky suggests, Wilkinson is an able writer and gifted observer. He has to be, for none of the three subjects he has chosen to write about in “The Riverkeeper” is especially compelling. Nor is the simple, unhurried style Wikinson brings to them. It’s the journalistic equivalent of anthropological “thick” description--a piling-on of detail that, when done skillfully, can be wonderfully evocative.

There is always the danger, though, of flaccidity and the over-accumulation of detail. Wilkinson is not immune to this. The Alaska section contains a sentence that goes on for four-fifths of a page (298 words--I counted).

The title piece is the most interesting, for Wilkinson has an individual to hang it on. That and the fact that Cronin’s major coup while patrolling the river has been a very nice bit of detective work, indeed: discovering that Exxon tankers were filling up with fresh water from the Hudson to bring back for their refinery on Aruba to use.

“The Blessing of the Fleet” is the least substantial section, an extended slice of local color.

“The Uncommitted Crime,” the Alaska piece, is the book’s longest. It’s at once a profile of a place, a study of a people (the Tlingit, the native inhabitants who make up most of the island’s population) and a bit of a polemic.

Wilkinson details the injustices that have been visited on the Tlingit by the white man, and many have been inexcusable--even heinous. Yet he does so in a way redolent of the sweetly reductive political simplicity that has become another characteristic of the latter-day New Yorker (think of Jonathan Schell’s “The Fate of the Earth” or Bill McKibben’s “The End of Nature”).

This trend complements the rustication, of course.

This is by no means a bad thing. But neither assumption is more or less artificial than the other. And Wilkinson’s Admiralty Island, Provincetown and Hudson River--in the considerable pleasures they afford as well as the intermittent exasperation they occasion--are very much New Yorker places of the current dispensation.

Next: Elaine Kendall reviews “The Accident” by David Plante (Ticknor & Fields).