The core of the Stampede is the rodeo. Contestants appear by invitation only and are competing for about $2 million worth of prizes, plus another $1.2 million for the chuckwagon racers who have their own competition.
They will do the things cowboys did: rope steers, wrestle calves and ride bucking bulls and broncs (note, to call them broncos is as naff as tucking your jeans inside your boots).
The broncs, known in the business as "rodeo rough stock", are bred specially at the Stampede Ranch, a stud that is home to about 550 horses that are genetically programmed to buck. In the rodeo an innocuous sheepskin "flank strap" is strung round their loins to infuriate them to kick and writhe so violently that they will dump anyone fool enough to mount them. Cowboys have to stay aboard for eight seconds to score a single point.
Stampede touches the whole city. For 10 days the unlikeliest folk become cowboys. Lionel Houliat is a serious kinda guy and general manager of Le Germain, a boutique hotel - stylish, contemporary and slap in the centre of town. It's at the top end of Canada's rating system. That befits Houliat, who has worked extensively in grand Swiss hotels.
But for his first Stampede he broke the dress code of a professional lifetime and came to work without a tie - and wearing jeans. The experience was so disconcerting that he had to ring his mother in France to tell her.
To Calgary generally, Stampede means an income over 10 days of about $675 million. Smithbilt Hats, which has been making cowboy headgear since 1919, will do 60 per cent of its year's business in the four months before Stampede and sell 40,000 straw hats alone.
The Alberta Boot Company expects to sell half its annual output - about 2000 pairs of handmade leather boots - in just four weeks.
There will be pancake breakfasts and sugary bags of mini-doughnuts on sale. Chocolate bars will be deep-fried and Buzzards Restaurant on 10th Ave will hold its 20th Testicle Festival with prairie oysters in dishes such as Alberta tender groin. They are grey, tasteless and have the consistency of liver.
There will be contests between blacksmiths and sheep-shearers, and sheepdog trials, illusionists and Indian dancing. Unlike the old days, when cowgirls also competed in the rodeo, a slalom horse race is now the only dedicated event for women.
My Stampede began as the festival itself did a century ago, with ranching. The Rafter Six Ranch is cupped in a wide curve of the Rocky Mountains, about an hour west of Calgary along the Trans-Canada Highway.
But Rafter Six is also a resort with log cabins, a wedding chapel and a lodge; there's a zip-line and white-water rafting, too. As much corporate retreat as home on the range, Rafter Six may seem a touch ersatz with its hefty pine-log architecture and cowboy kitsch.
Page two of my Bedroom Information Pack was titled "History of the Brand" - referring to the mark burned on the flanks of livestock. The first Stampede in 1912 had the same sense of detachment. That year's poster advertised "The Last Great West: Greatest Frontier Days' Celebration Ever Attempted".
With the prospect of cow-town Calgary developing into an industrial city, the fear was that the Old West would evaporate along with that the tough, frontier way of life.
Stan Cowley, Rafter Six's owner, has a big collection of Western memorabilia including a Concord stagecoach, a horsedrawn vehicle built in 1870 that appears regularly at the Stampede. It has the distinction of being the only stagecoach in Alberta to have been held up by outlaws. That was in 1886 when it was robbed by the Crackerbox Jack gang. (The "Jack" came from their masks, made from fragments of a Union flag.)
This will be Stan's 72nd consecutive Stampede. He was four when he attended his first and rode on the float entered by the Hudson's Bay Co, Canada's oldest company, for which his father worked.
Two years later he accompanied the Nakota Sioux, and lived with them in their village, which to this day is set up outside Stampede Park. It was the beginning of a lifelong association with Canada's First Nations people.
At age 13 he was made a Sioux blood brother with Chief Walking Buffalo.
"They took me to a Sundance gathering and were all in paint. When they took the knife out I thought they were going to eat me," he recalls.
Now he enjoys the rare honour of being a chief in all five of Alberta's principal First Nation bands.
This year, Stan and his family planned to ride for five days in a wagon train to the Stampede. He is a man steeped in the lore of the West which, for him, is embodied in rodeo: "The skills in rodeo were skills that all came from the ranch." Chuckwagons, cowboys' mobile kitchens, were raced as the cooks from each outfit would try to beat each other to the choicest campsites.
At the Stampede the wagons, driven by men with names such as Troy, Cody, Chanse, Chad and Logan, race every night in a tournament that culminates on Showdown Sunday. Then the final four compete for the championship and $122,000.
Today's racing wagon is a stripped-down version of the lumbering real thing, more camping-trailer than prairie schooner. As a nod to the old covered wagon, a tarpaulin bonnet is hooped over the back - just big enough to take a sponsor's name. Nothing can be done to make it faster, or slower, come to that, as there are no brakes. Design and weight are precisely specified.
The drama comes with the horses. Each wagon is drawn by four thoroughbred racehorses, almost all recently retired from the track, and attended by two "outriders". With outfits travelling at 65km/h, the sport is dangerous for men and horses. Several drivers have been killed - one on the opening night of the 1999 Stampede - and three horses died in 2007 and 2009.
Drivers now wear protective vests, though few have abandoned their cowboy hats for helmets, and the demands on their horses have long attracted the censure of animal-rights campaigners. Some would like to see rodeos banned.
The organisers say that the number of appearances a horse can make is restricted and each is examined regularly by vets. This year the University of Calgary is monitoring some chuckwagon horses to see if their fitness and training might be improved.
But although the vets can gauge heart rates and blood counts, they can't measure the sheer excitement of four wagons cornering full tilt on a 8-12km track, pursued frantically by the posse of outriders in a thunder of hooves and dust.
It's a cross between a soapbox derby and the chariot race from Ben Hur.
A hundred years ago, the Stampede's founders boasted of "Positively the Greatest Aggregation of Expert Cowboy Talent in the Range World". Today the organisers settle for "The Greatest Outdoor Show on Earth".
Whatever else died with the Old West, hyperbole didn't.
CHECKLIST
Getting there: Air New Zealand flies direct from Auckland to Vancouver. Local airlines connect to Calgary.
Details: This year's Stampede is on July 4-13.
Further information: See calgarystampede.com and visitcalgary.com.
