In a hillside just outside of town, the road they used to call America's Main Street comes to a dead end.

Pitted and cracked, overgrown with weeds, the old U.S. Route 66 runs for a mile or so along the interstate that replaced it--until the superhighway, curving, cuts the old road off.

The scene here is repeated in many spots along the 2,200 miles that Route 66 once spanned between Chicago and Los Angeles, with chopped-up fragments of highway all that remain of the old road. In other places, 66 is a business route connecting sleepy villages to the distant interstate. Elsewhere, it loops stubbornly off on its own through rugged territory, all but abandoned save for the tumbledown remains of filling stations, diners and motels along the roadside.

Once it was America's most famous road. John Steinbeck chronicled the Joad family's westward migration along 66 in "The Grapes of Wrath." Tod Stiles and Buzz Murdock combed the road for adventure in their Corvette every Friday night in a TV show named after the route. Nat King Cole, the Andrews Sisters, Chuck Berry and The Rolling Stones all promised "You get your kicks on Route 66." And Phillips Petroleum Co. adopted the Route 66 symbol for its brand of gasoline--although the company says the Phillips 66 name is actually derived from the gas's formulation.

For millions of Americans, Route 66 was The Way West--a road of escape for Okies driven out of their land during the Depression, or a route of retreat for countless vacationing families at a time when Holiday Inns were just ordering their first neon signs and McDonalds had not yet gilded its arches.

It went through big cities like St. Louis and Oklahoma City and tiny towns like Galena, Kan., and Two Guns, Ariz. It crossed the mighty Mississippi and creeks too small to have names. It passed through the plains, traversed the desert, skirted the Grand Canyon and climbed the Rockies, along the way providing views of scenery unimagined at either end of the route.

But now, America's Main Street is little more than a side street. The road once lined with Burma Shave signs and billboards urging motorists on to "Tucumcari Tonight!" has given way to five separate interstate highway links: I-55, I-44, I-40, I-15 and I-10.

When a five-mile stretch of I-40 is opened outside Williams, Ariz., later this year, the last chunk of Route 66 will finally be bypassed, and a motorist will be able to drive the route from Michigan Avenue in Chicago to Santa Monica Boulevard in Los Angeles without ever traveling over the old Route 66.

The gas stations, motels, souvenir stands and restaurants that make Williams the quintessential tourist town no longer will be able to count on the route's east-west traffic to provide customers automatically. As has happened in other towns along 66, many businesses in Williams either are packing it in or packing up and moving closer to the interstate exits.

The man who led the fight for Route 66 during its glory days and its eclipse was Jack Cutberth, the man they called "Mr. 66." The Clinton, Okla., barber ran the Route 66 Association, an alliance of businessmen along the route who lobbied for road improvements and promoted the route in advertising.

In his final campaign, Cutberth tried to have the interstate that replaced the old route named I-66, but that designation was given instead to a stubby stretch of highway that connects Virginia with the District of Columbia.

Cutberth died in 1978, and the association faded away a few months later. But his 78-year-old widow, Gladys, who was the group's secretary, still fills the occasional requests for Route 66 information and promotional material, and remains a store of history and anecdotes about the road her husband loved.

"I don't know why it fascinated him so," Mrs. Cutberth says. "It wasn't a money-making job, but it was work my husband just loved."

The Cutberths traveled Route 66 several times a year, recruiting new members for the association and distributing promotional material such as postcards and window decals that celebrated Route 66 as "The Route America Travels."

Mrs. Cutberth says Route 66 had a quality that made it different from the modern interstates. "There's just something about it," she says. "It's more--I don't know if you could say human, because I don't know if a road can be human--but there's a personality that can be felt."

Driving what's left of Route 66 certainly is different from traveling on the interstate. If the interstate system is the backbone of America's transportation system, then roads like 66 are its heart and soul.

While the interstate zooms arrow-straight through the countryside, 66 meanders, twisting and turning as it explores America's heartland. The ever-changing mosaic of roadside scenery, buildings and small towns, even of road surfaces, sets 66 apart from the well-groomed and usually anonymous suroundings of its modern replacement.

In southwestern Missouri, at Joplin, it sprouts from the interstate and takes off on its own, slicing a sliver off Kansas and then heading into Oklahoma. Miles from the interstate, 66 still lives up to its Main Street nickname. The speed limit dwindles at the small towns along the way, and in many it is the only street worthy of stoplights.

The names of these towns can be found along Route 66 on the front of the post office or town bank, but more often than not they are shouted from billboards and attached to slogans that attempt to distinguish each town from the burg down the road. So Chandler, Okla., boasts that it is "The Pecan Capital of the World," and Davenport, Okla., is "A fine town with friendly people."

Other signs boast of the attractions along the way--buffalo farms, souvenir stands and other tourist attractions. Mom-and-pop restaurants offer food to the traveler, tiny motels bed down the weary. These are the kinds of places that, when using the word "corner" in their names, spell it with a "k" (except one roadhouse east of Tulsa perversely named "Kountry Corner").

Route 66 and the interstate again become one outside Oklahoma City and head west with only occasional traces of the old road, crossing into Texas, New Mexico and Arizona. In Joseph City, Ariz., a string of souvenir shops lining old Route 66 sits abandoned, weathered signs advertising half-price "bypass" sales on petrified wood, moccasins, and turquoise jewelry. Cars speed by on the interstate a frustrating 100 yards away, but the nearest exit is miles off. Not far away, cattle graze on the weeds peeking through the old pavement. About the only things rolling on this stretch of Route 66 these days are tumbleweeds.

The glory that once was Route 66--and its dereliction--are most visible in western Arizona. In Seligman, the black asphalt of an I-40 exit becomes the salmon-gray of Route 66's cement pavement as 66 strikes out stubbornly on a route completely different from the highway, through tiny towns not included in the "Route 66" song's famous litany of place names:

Now you go through Saint Looey and Joplin, Missouri,

And Oklahoma City is mighty pretty;

You'll see Amarillo; Gallup, New Mexico;

Flagstaff, Arizona; Don't forget Winona,

Kingman, Barstow, San Bernardino.

When you make that California trip,

Get your kicks on Route 66!

Towns like Hackberry, Peach Springs and Hyde Park, Ariz., are practically deserted, dotted with wrecked filling stations and stores and littered with cars abandoned like the Nehi bottles their occupants once tossed out the windows. Cactus, sage and yucca plants provide what vegetation there is in the flatlands surrounded by towering mesas. And watch out for rattlesnakes.

An occasional freight train moves along the Santa Fe tracks that parallel Route 66 for much of its length, a reminder of the days when drivers on 66 raced the railroad's crack passenger train, the Super Chief. One can drive for miles without seeing another car; get out on the side of the road to admire the scenery and the only things you'll hear are the wind, an occasional bird, and the soft creaking and clanking sounds a warm car makes at rest.

Sixty-six rejoins the highway in Kingman, and they continue into California together with no indication--even on 20-year-old road maps--that the old route once might have traced another path. But south of Kingman, Oatman Road pulls off the highway to the right, and for the next 70 miles, one can duplicate exactly the final leg of the Okies' drive to the promised land of California. For Oatman Road really is the old 66, one of the first stretches replaced by interstate, 30 years ago.

Just barely two lanes wide, weathered and bumpy, the road snakes treacherously up a steep grade through the mountains between Kingman and Needles, Calif. This is no road for the meek: top speed is about 20 miles per hour, and a wrong move on one of the hairpin turns can send a car plunging off a 200-foot embankment unhindered by guardrails.

A few miles on, painted rocks on a hillside form a large sign identifying Ed's Camp, a throwback to the days when westbound travelers, running low on funds, would trade anything they had for water and enough gasoline to make it to California.

Marked by a towering saguaro cactus and an old-fashioned gas pump, the ramshackle buildings of Ed's Camp seem little changed today from when the Okies stopped there half a century ago. Keith Gunnett, nephew of the founder, Ed Edgerton, presides over Ed's Camp now, showing visitors the collection of Model-T parts, furniture, patent medicines, household goods and other things Edgerton collected in the 60 years he ran the place.

"They were trading off anything they could get for gas," Gunnett says. "That's where most of this stuff comes from."

The road winds through the spectacular, rocky beauty of Sitgreaves Pass to Oatman, once a gold-mining center and now little more than a ghost town. Burros wander the streets. Outside town, jackrabbits--"Hoover Hogs," the hungry Okies called them--scoot across the road that leads to Needles, 2,000 feet below. Another town, Gold Roads, a few miles up the road from Oatman, has disappeared altogether.

Interstate 40 cuts through the mountains many miles south of the old Route 66, taking travelers from Kingman to Needles in considerably more safety, and making Oatman and Gold Roads symbols of what has happened in many places where the interstate has bypassed 66.

It's that kind of desolation that worries the people of Williams. Tourism is big business for Williams: its slogan is "Gateway to the Grand Canyon," which is about an hour away. Many in the town worry about what will happen to the businesses that line their stretch of Route 66 after the last chunk of I-40 bypasses the town.

Yet Filo Cothren, the owner of the town's last Phillips 66 station, believes that, after a bad year or two once the bypass is opened, business will return. "It will begin to come back," says Cothren, who's been selling gas in Williams for 40 years. "Every town that's been bypassed has come back."

Even though the interstate has taken its place and absorbed its traffic, Route 66 will live on, in the memories of those who traveled it, of those who made their living off it, of those who lived along it.

"There's so much history on 66," says Peggy Sizemore, who operates a filling station on I-40 as it cuts across the old route in Lupton, Ariz., on the New Mexico border. "This Interstate 40 will never leave history--everything is too fast on it."

"People remember it," Mrs. Cutberth says of Route 66. "I call it the highway that refuses to die."