When railroad travel was still convenient, I often wondered why the trains bothered to stop at places like Wilmington or Trenton, to say nothing of Hoboken. Now, for most of us, America's old industrial towns have almost entirely faded from memory. The freeways bypass them.

One finds the names of these "gritty cities tucked away on the backs of cough drop boxes, the bottoms of thermos jugs, and the labels of shirts you wear every day," say Mary Proctor and Bill Matuszeski, who have just published a book about them. Only now, as America's values are changing, and as we are learning to appreciate cities and history, are these not-so-faraway places being rediscovered. They have, in fact, just rediscovered themselves.

What a marvelous term -- gritty cities!

And what richly varied, intriguing places they are!

"Gritty Cities" (Temple University Press, $17.50 hardback, $9.95 paper) depicts in words and an abundance of photographs the romance of their smokestacks, derricks, mills and warehouses, seemingly built for eternity amidst canals and falling waters and against a setting of domes, spires, towers, gables and turrets, rows upon rows of houses and public buildings and spaces bursting with civic pride.

These cities grew early in the industrial revolution, nourished by water power, coal, railroads and incredible inventiveness. They produced horseshoes, stoves, sewing machines and other implements of an agrarian society.

At the end of World War I, we had become an industrial society. Reduced freight rates had created a national market. Big cities took over and got bigger.The small, gritty cities declined.

All of them had prospered and declined in the same period and in the northeastern states. But each of the 12 cities portrayed in this book is distinct.

Allentown and Bridgeport, the authors say, "look solid, prosperous and cheerful -- the kinds of places where every American boy and girl not raised on a farm should have been brought up."

"Bethlehem is a schizophrenic at peace with both of its selves" -- its Moravian tradition and its industrial ambition. "Hoboken in a city of front stoops, iron railings and walkups."

In Lancaster, some of the colonial houses "are small enough to have emerged from nursery rhymes, but nearly all exude confidence they will take the next two centuries of use in their stride."

Norwich looks like many other New England towns. Paterson was founded to create the first indigenous American industry, independent of England. "Reading looks like a working-class San Francisco." Trenton teases the eye with its architectural contrasts.

Troy is still the kind of city Saint Nicholas and his reindeer are usually shown to be skimming over. Waterbury has suffered more than the others from fire, highways and urban renewal. Wilmington somehow seems "better able to pick itself up, dust itself off, and keep on trying."

But all gritty cities seem to have been hurt more by federal highway and urban renewal bulldozers in the 1950s than by economic change and depression in the 1920s and '30s. In Paterson the New Jersey highway department still holds a number of cherished old mills -- and woefully neglects them. In Wilmington quick and ruthless urban renewal leveled 26 blocks of an old, black neighborhood.

Housing in these cities is in better shape than the fashionable lament of urban decay would lead one to expect. "In some cases, what initially appears to be decay later turns out to be planners' blight, long-awaited destruction for urban renewal or for a highway."

Now the changing mood in America is helping the gritty cities to recover.

Troy and Paterson have already become centers for the emerging study of industrial archeology, supported by the Smithsonian Institution. Old mills, factories and warehouses are being recycled into lucrative "factory outlets," artist studios and even luxury apartments.

Factories in the midst of small cities have lost their importance for American manufacturing, say the authors of this book which is substantial enough to be used as a text and, oddly enough, also good reading.

But the gritty cities are rich in architectural legacy. Traditions are better remembered in them than in big cities and suburbs. Their scale is human. And all that gives them a new national importance.

It will give a special flavor to the effort of designing new forms of commerce and urban living.