They swear me in, in a downtown hotel in Sacramento. Big Rich Tatman, California Division President of the National Pony Express Association holds the oath high, dressed in white Stetson, yellow bandana, snappy waistcoat and jingling spurs. It's a solemn moment. Rich has ridden the Pony Express trail, night and day, more times than Buffalo Bill Cody scoffed a bison steak and fries. "Now you're entitled," he says, "to climb in the saddle." He shakes my hand.
Buffalo Bill, allegedly one of Big Rich's predecessors, was one of the originals who rode from St Joseph, Missouri, 2,000 miles to Sacramento in 1860. "Neither storms, fatigue, darkness, mountains and Indians, burning sands or snow must stop the precious bags. The mail must go," wrote one supporter of the venture on 3 April, the day the first rider high-tailed west.
Today, 150 years later, in the teeth of a flurry of celebratory fanfares, the Pony Express has become a legend best explained by the universal twin enticements: speed and danger. "American virtues," declares a guy on K Street, the route the riders would have galloped as they headed towards the Sacramento River.
This year to celebrate the survival of the legend, the Pony Express Association will ride the old route, now criss-crossed by highways, houses, office blocks, dense traffic, by all of the 21st century's markers of madcap life. At chosen towns along the route through the states of Wyoming, Nebraska, Utah and Colorado, fans will gather. The riders will pause.
"Hey, catch the statue in the Old Town," says my informant. "Head for the Capitol, straight down L Street, dip through the subway towards the river – hear a splash and you've gone too far!"
Governor Schwarzenegger's Capitol building looks like a Christmas cake: pure icing, wearing its dome like a po-faced crown. It is utterly splendid, ringed by palm trees, drooping willows and thick-trunked oaks.
I meander and gawp through purple shadows and manicured, jasmine-scented gardens, reaching the Old Town – the Wild West resurrected in its now tamed, tourist-boarded guise – in just 15 minutes.
Make no mistake, though it looks like a Hollywood rent-a-set version of reality, built to showcase stage-managed shoot outs under the blaze of the midday sun, the place is real. It exudes authentic dilapidation. I wander the suitably creaking boardwalks, passing saloons, a busy tattoo parlour, stores and railway sheds. Above me rickety balconies, now deserted, once vibrated to dancing madams yelling the odds at drunken cowboys.
And then I see it, across the street from the small Wells Fargo Museum, unmistakeable in its profile: the galloping steed, the speeding rider, the Pony Express bringing home the mail. The statue is so streamlined, poised and dignified, you can almost hear the hoof beats thundering towards you, entering history, trapped in a miniscule window of time.
The Pony Express lasted just 18 months. The riders covered 616,000 miles and carried 35,000 items of mail. Judged as a business it never took off and flopped spectacularly, accruing debts that amounted to more than $10 for every item it carried in its short history. What quashed it was the railroad, traversing the plains, combining romanticism, glamour and a capacity to carry just about anything. The newly invented telegraph thumped the final nail in the coffin, sending messages coast to coast in the blink of an eye.
And yet, as I gaze at it, the statue and what it stands for – pioneering doggedness fuelled by enterprise and courage – comes alive. It transcends the brevity of its history. It seems timeless.
Oddly, no one else pays attention. Tourists instead head for the Sacramento History Museum, where the Pony Express's role in the city's birth pangs is mysteriously ignored. After a while I follow suit and browse the Wells Fargo Museum, stroll the river front, and that evening enjoy a steak on the upper deck of the Delta King, which seems so rootin' tootin' authentic I half expect to see Bret Maverick dealing cards at the polished bar.
Yes, Sacramento safeguards its history. On the edge of the downtown high-rise is Sutter's Fort, the earliest trace of white habitation in the area, now restored to its dominant 1850s self, and beside it the California State Indian Museum provides glimpses of a culture warped by the influx of teeming prospectors lured by the 1849 gold rush.
The city's prosperity may have wobbled, but hasn't faltered, despite California's current economic nose dive. The Pony Express's go-getting ethos and esprit de corps has somehow infiltrated and stuck, and I'd love to be here on 3 April, when the chosen rider in his signature yellow bandana high-tails east from Old Sacramento bound for Folsom.
I've even bought that yellow bandana, acquired the Stetson. And now that I'm sworn... I harbour the fantasy. Oh yes. All I need now – a footling detail – is the horse.
Travel essentials: Sacramento
* Sterling Hotel (001 916 448 1300; sterlinghotelsacramento.com ). B&B starts at $152 (£101).
* California State Railroad Museum (001 916 445 6645; csrmf.org ).
* Sutter's Fort State Historic Park (00 916 653 6995; parks.ca.gov ).
* Wells Fargo Museum (001 916 440 4263; bit.ly/fargomuseum ).
* Pony Express Trail and Anniversary: nps.gov/poex