DINERS -- those clean, gleaming roadside palaces of pie and pancakes -- are perhaps the best-known symbol of America. They're ubiquitous in popular culture: Edward Hopper painted them. Hollywood set movies in them -- from ''Little Caesar'' to ''Diner.''
Here in America's historical heartland -- just a few miles from Revolutionary war battlefields -- the small Museum of Our National Heritage recently opened the country's first diner exhibit. The culmination of the lifework of local diner aficionado, Richard J.S. Gutman, the photographs, artifacts, and ephemera reveal how central these original fast-food establishments have been to life in the United States.
''They're icons of American culture,'' Mr. Gutman says. ''When you see one, you know it's small-town USA: They give a warm, good feeling.''
Diner lovers can thank journalists. The first diner came about in 1872 when young Walter Scott stocked a wagon with sandwiches and homemade foods on a street in Providence, R.I., to serve newspapermen on the night shift.
''Walter Scott had the idea you could earn a living serving people at odd hours,'' Gutman says. ''It was an instant hit. He made a lot of pies and a lot of chicken sandwiches, but not a lot of money.''
The eateries, as a series of 3-D postcards in the exhibit reveals, changed as public tastes changed, from wagons to aluminum-sided, factory-produced boxes with tiled floors, a counter, and a row of stools. In the 1920s, tables were added for ladies who weren't comfortable sitting at the counter, and the diner traded its wheels for a foundation. In the '60s, diners had been transformed from sleek machines to brick, stone, or tile restaurants almost unrecognizable as diners. But as they evolved, one thing remained: The cooking was usually done behind the counter, for everyone to see.
Most were built on the East Coast because shipping costs made it too expensive to move them far. Massachusetts alone has 140; New York, New Jersey, and Pennsylvania have even more.
But these days they're going all over. One just moved from its longtime home in Danvers, Mass., to Madrid.
''A transplanted New Yorker had one shipped to Truckee, Calif., because he was homesick,'' Gutman says.
The exhibit comes out of Gutman's 20-year obsession with these movable feasts. Back in 1971, as an architecture student in Allentown, Pa., he casually took a group of British architects to a diner as part of a city tour. To Gutman, diners were just another piece of city furniture. He had been eating in them since he was a child; there were four within walking distance. But the Brits' enthusiasm opened his eyes.
Gutman started eating in, documenting, and collecting from diners all over the country. This isn't exactly a hobby; it's more like his life: ''I've eaten in 600 to 700, list 1,400 in my book, [''American Diner: Then and Now,'' HarperPerennial, 1993], and have 2,500 on my database.'' He even makes some of his living as a consultant on the restoration of diners.
Exhibit visitors don't exactly get to go inside a real diner and have an ''Adam and Eve on a raft'' (poached eggs on toast), but they do supply a real Frialator (for french fries), a grill, and an ancient menu board (Ham Steak Hawaiian: $1.50, Sirloin, $2.70).
Also on view are a diner quilt, a diner shirt, hat, and T-shirt, a big plastic diner sign, a counter from a 1920s Worcester Lunch Car, stools from different eras, thick china coffee mugs, even matchbooks.
The big hit of the exhibit is an interactive 1950s-era play diner. While parents sit in red leather ette seats and wait to be served, children ''cook'' hotdogs, hamburgers, and pancakes on a fake grill. Another interactive space invites visitors to figure out diner slang for food that's practically obsolete now: ''Hounds on an island'' (frankfurters and beans), ''sweep the kitchen'' (plate of hash), ''bale of hay'' (shredded wheat).
The culmination is a short video showing Buddy's Truck Stop, a real workingman's diner, in Somerville, Mass. Counterman and owner John Barrett there says he's ''done 1 million eggs.''
In the video, a customer looks at the cook's big belly and cracks, approvingly, ''Never trust a skinny cook.''
*''American Diner: Then and Now'' runs through July at the Museum of Our Natural Heritage in Lexington, Mass.