Some archeologists dig ancient Greece. Others hunt old bones in Africa's Great Rift Valley or investigate Indian trash heaps in Illinois. But Peter Smith prefers skulking U.S. 1, the old main drag between Washington and Baltimore.

Smith is a commercial archeologist, one of a new breed that delights in the modern Americana of gas stations, diners, drive-in theaters, motor courts and even fastfood establishments.

"This stuff is a legitimate expression of today's culture -- it's just as worthy of studying and preserving as 18th-century taverns," he says.

By today's culture, Smith doesn't really mean the 1970s, a decade he feels is characterized mainly by a "corporate sameness" that crowns fast-food restaurants with cosmetic mansard roofs and gas stations with phony colonial facades.

Instead, Smith likes to roll back the clock to 20 or 30 years ago, when the gaudy melon flower of American free enterprise was in full bloom and "everybody was out for themselves," touting their wares in neon signs that could be seen by people traveling an incredible 50 miles an hour.

"Basically, commercial archeology is the study of the tangible aspects of the influence of the automobile on the land," says Smith, who has lectured on the subject to such groups as the National Trust for Historic Preservation.

The most fertile ground in America for such exploration is Lost Angeles. But, since lOs Angeles is too far away, Smith finds, U.S. 1 an acceptable initiation into commercial archeology.

"It's almost a time capsule, a ghost town. The highway has lost its economic base -- because of the Baltimore-Washington Parkway and I-95," he says. "But there's no reason to tear these old things down -- that would cost money."

One of the highway's campiest landmarks -- The One-Stop Flea Shop, a flea-powder salesroom shaped like a dog -- has been torn down, but other roadside relics remain.

Atart in beautiful downtown Hyattsville, where Route 1 functions as Main Street. Appreciate a classic of its type: The revolving punching-bag neon sign advertising the Lustine Chevrolet dealership.

"You can tell from that sign that this is an older highway," says Smith. "You could only see that sign if you were going slower than 50 mph. The first neon sign was developed in Paris in 1921, and now neon is fading out and being replaced by fluoresent lighting. Neon is becoming an are form. There are antique shops in Los Angeles that sell nothing but neon." Just past the College Park campus of the University of Maryland, Smith notes with a sigh that a lot of "upgrading" is going on. He also points out a mild example of a popular highway phenomenon -- product personification.

"What does that restaurant sell?" asks Smith rhetorically. The red-yellow-and-white creature perched above the door answers the question: chicken.

Another roadside landmark became a recent cause celebre for commercial archelogists, according to Smith. The Sankey Milk Bottle, a larger-than-life symbol of an attached dairy establishment in Tauton, Mass., was about to be torn down to make way for a gas station. Instead, a highway archelogist bought it and talked Hood's, a New England dairy firm, into restoring it.The restored milk bottle is now displayed at the Museum of Transporation in Boston.

Near Beltsville, we see an example of what Smith calls "a natural combination of two of the major influences on 20th-century civilization" -- Sidney Lust's Drive-In Theater, whose name apparently personifies the product. Lust's, adorned with Greek comedy and tragedy masks, has seen more prosperous days.

A little past Beltsville w e stop to take a picture to add to Smith's collection: a neon sign inviting motorists to stop at Vet's Liquors. The vet, his blue neon uniform grown tawdry with time, stares at us with yellow neon eyes. We vow to return at night to watch him glow in the dark.

From the city to the Beltway, the old highway is still used. But now we're beyond the Beltway, where the only enterprises that seem to survive sell red, white and blue cement birdbaths in the shape of seahorses. Dotted among such shops are abandoned motels, although the word motel is an anachronism in these cases, according to Smith.

"The word 'motel' wasn't commonly used until the '50s," he says as we pull up in front of the Canary Cottages. Each unit has a connecting garage. So does Tim's Motel, which boasts U-Dial-Heat, and the Cedar Motel, clad in Permastone. But many other motor courts along U.S. 1 are abandoned.

"Most of the early motor courts were Mom and Pop operations," says Smith. "You know how the big chains advertise 'no surprises?' Well, at Mom and Pops there were often surprises. Until after World War II, the tourist court was considered the poor cousin of the hotel -- a place which catered to the 'hot pillow trade,' to use J. Edgar Hoover's eloquent phrase. Once the potential of roadside overnight accommodations was realized they leaped out of the Mom and Pop stage of merchandising and into the arena of big business. Look at the Holiday Inn at the intersection of Route 1 and the Beltway. It faces the Beltway. Look at the old Del Haven right next door. It faces Route 1."

Just past the junction of Route 175, we come to Smith's favorite sign. It's huge neon rectangle itemizing the attractions of Pool's Evergrrn Inn Bar: pool tables, car ryout, beer, wines, liquors, miniatures, motor court -- the last being some detached log cabins painted red.

"Some of the neon is shot," says Smith regretfully. "If I ever had the time, I'd try to get this sign nominated to the National Register of Historic Places."

Beyond the Bonheur Pet Cemetery, a memorial pet park landscaped like a Japanese garden, new indsustrial parks begin to appear between the abandoned motels. Smith shakes his head.

"I'm afraid if people find they can use the land profitably for industrial parks, some of this good stuff will be torn down," he says. On the outskirts of Baltimore, we turn around. Smith is pressed for time and considers returning via 1-95, but decides against it. "Trees are not the environment of the car," he says. "This is a lot more fun."

Besides, we have skipped one of the highway's highlights. It lies on U.S. 1 going south through Laurel, where the highway is divided. We pull up at a Big T Family Restaurant. Which used to be a Tastee-Freeze and, before that, a McDonald's. Not the bland, inoffensive kind of McDonald's you see today, but a vintage Ronald with redand-white striped Op Art tile exteriors and giant golden arches that hovered over the building like a halo.

"The early restaurants were classic examples of pop architecture," says Smith, but "they're disappearing as McDonald's tries to bring class and convert many of its operations to family restaurants. I lament that. A little bit of Americana disappears with each modernization. One original redand-white McDonald's should be preserved somewhere."

It's probably too late to save the franchise in Laurel.The arches that used to envelop it are gone, and brick veneer covers the redand-white stripes -- almost. But if you walk around the back of the building you can still see a row of red-and-white tiles framing the bathroom window.

"What a terrific place this will be for an archeologist 50 years from now!" Smith says.