Officially, it's called California State Route 1. Most Californians refer to it as Highway 1, or simply "the One".
Its designation doesn't denote any special strategic or economic importance. For most of its length, Highway 1 is a two-lane road that carries relatively little traffic, at least by American standards. Yet the name could hardly be more appropriate, since it's surely one of the world's supreme scenic coastal routes.
It runs for more than 1000 kilometres from tiny Leggett, 320km north of San Francisco, to Dana Point, on the southern fringe of Los Angeles. For almost all that distance,
Highway 1 hugs the spectacular and rugged Californian coast, diverting inland only when it encounters obstacles such as the vast Vandenberg air force base near the town of Lompoc.
Along the way, the road passes points of interest whose names will be familiar to many New Zealanders: the magnificently eccentric Hearst Castle at San Simeon, the imposing wilderness of Big Sur, the historic city of Monterey, the ultra-chic community of Carmel and the wooded hills of arty Marin County. And, of course, it crosses the fabled Golden Gate Bridge.
But there are plenty of other attractions, not so well known, that make Highway 1 a rewarding road trip. There are whales to be spotted (grey, humpback and blue whales all migrate along the coast), redwood forests to camp in, wilderness trails to be hiked, wineries to visit and charming little seaside towns to explore.
The best-known section of Highway 1 is the one that runs between San Francisco and Los Angeles, a distance of about 700km that's best driven north to south, for the simple reason that the right-hand side (remember, you're in America) is closest to the sea, offering the best views.
Motorcyclists love this route. So do sports-car drivers. The road's popular with cyclists too, for the good reason they can wallow in the scenery without worrying about heavy traffic.
On the most scenic sections of Highway 1 the biggest vehicles likely to be encountered are RVs (recreational vehicles, or campervans in New Zealand parlance). There are few towns along the way and most consist of little more than a petrol station, a cafe and a motel.
California may be America's most populous state, but part of Highway 1's charm is that it reminds Americans of a time when roads had only two lanes and were free of the strip malls, motels, gas stations and fast food outlets that clutter the freeway system.
The most scenic segment of the route starts at Monterey, a picturesque city made famous by John Steinbeck, as the setting for his novels Cannery Row and Sweet Thursday. These days the city is better known for its superb aquarium, located on the same Cannery Row that inspired Steinbeck's book. (There's an excellent museum dedicated to him at Salinas, not far inland from Monterey.)
Immediately south of Monterey, it's worth taking a loop known as the 17 Mile Drive which passes through the community of Pacific Grove - once an artists' haven, now noted for its Victorian architecture - and Pebble Beach, home to one of America's most exclusive golf courses. Here too is one of the world's most photographed trees: the famous Lone Cypress, which stands on a rocky outcrop above the Pacific.
Carry on south and you soon reach affluent, eco-conscious Carmel, whose residents are so allergic to visual blights that street lights, parking meters and even house numbers are forbidden. Clint Eastwood was the town's mayor in the 1980s and still has a home here; other residents include crime novelist James Ellroy, actress Doris Day and former Monkee Mike Nesmith.
After Carmel, Highway 1 leaves behind the comforts of affluent, urban California. Here the mountains of the Santa Lucia Range push out to the coast and the road becomes narrower and winding. This is the stretch of coast known as Big Sur, a name derived from the Spanish el pa is grande del sur, or "big country of the south".
And it is big. In places the road clings precariously to almost-sheer slopes several hundred metres above the sea. No highway existed here till 1937; the terrain was too forbidding. Construction took 18 years, much of the work done by convict labour from San Quentin and Folsom prisons.
Big Sur's remote grandeur once made it a much-favoured retreat for artists and writers, among them Henry Miller and Jack Kerouac. Even today, much of the Big Sur coast has no electricity supply. The tiny town of Gorda - a popular whale-watching spot - runs its own generator, subsidised by everyone who stops there to buy petrol.
The hills of Big Sur eventually give way, near San Simeon, to a gentler but still scenic coastline of broad, sandy bays and rocky inlets. At Point Piedras Blancas, tourists brave the often bitterly cold wind to photograph massive elephant seals that haul themselves up onto the beach to sunbathe.
San Simeon is a modest little town that would hardly warrant a mention but for one thing: the wondrously over-the-top castle built on a commanding hilltop for newspaper magnate William Randolph Hearst, the man whose ambition and ruthlessness inspired Orson Welles' great 1940 film Citizen Kane.
Built over several decades in ornate Spanish Revival style and crammed full of priceless antiquities and works of art collected from all over the world, Hearst Castle is a monument to excess and eclecticism. The castle is so big - 56 bedrooms, 61 bathrooms, 19 sitting rooms - that no single tour can take it all in; instead, there's a choice of six.
From here to LA, about 370km away, Highway 1 is busier and less scenic but still pleasant, passing through a succession of beachside towns and the attractive university town of San Luis Obispo, centre of a thriving wine region.
The last point of interest before reaching LA is Malibu, where celebrity spotters can scan the beachfront sidewalks for a glimpse of the Hollywood stars and rock gods who live there.
For those with a taste for the road less travelled, an appealing alternative to the San Francisco-LA route is the section of Highway 1 north of San Francisco. It's quieter and less typically Californian but the scenery is every bit as spectacular, with a wild, brooding quality all its own.
The road parts company with Highway 101, one of California's major north-south arteries, soon after crossing the Golden Gate. From here the One sets a gentle pace, winding through the redwood forests of Marin County before emerging on a wild, dramatic coast where every bend reveals a view more arresting than the last.
The road is often narrow and winding, hugging the edge of dramatic cliffs and skirting deep, rocky coves where massive beds of kelp swirl in the surf. Occasionally, the highway ducks inland, passing through rolling farmland and picturesque meadows.
The few little towns along the way - Olema, Valley Ford, Gualala, Bodega Bay (the setting for Alfred Hitchcock's 1963 thriller The Birds) - are charming and untainted by tourism.
At tiny Point Arena, you can admire what must surely be one of the most exquisitely restored art-deco cinemas in the world.
Quite apart from all its other virtues, Highway 1 is an agreeable way for New Zealanders to ease themselves into driving in America. Driving the One is pretty much like driving at home; the biggest risk is that you'll be so hypnotised by the scenery you'll forget which side of the road you're supposed to be on.
- Fairfax Media