The Duke and Duchess of Cambridge helped usher in festivities at the Calgary Stampede and visited the city's zoo on the final day of their Canadian tour, before flying to California Friday.

The couple began the day by greeting the throngs lining the Stampede parade route before triggering the official start of the city's annual world famous rodeo. They drove the route in reverse to the delight of one of the largest crowds of their nine-day Canadian visit. Officials said they estimate 425,000 people were in attendance.

The pair both wore their boots and white cowboy hats. While the duchess chose a blouse by Alice Temperley, the young duke drew some attention for wearing what appeared to be the same jeans and green checkered shirt he had donned on Thursday.

The couple did not take part in the actual parade, however, due to security concerns.

Instead, William and Kate drove from its end point to the start, where they met with dignitaries including Prime Minister Stephen Harper and Stampede parade marshal Rick Hansen. The couple then pressed a special red button, triggering a chuckwagon horn and a barrage of fireworks to officially launch this year's Stampede-opening parade.

The couple then made their way to the Calgary Zoo to tour environmental preservation displays. Alberta Premier Ed Stelmach and his wife, Marie, accompanied the Duke and Duchess, who had ditched their cowboy clothes for more formal attire. Kate wore a scarlet coat-dress and the prince opted for a blue suit.

The royals were also due to attend an Alberta government reception and have a private meeting with homeless youth. A provincial scholarship, created in honour of their visit, was expected to be announced.

Before departing Calgary, the couple spent time at a mural honouring Canadian soldiers killed in Afghan war. They bowed their heads in a moment of silence before inspecting a guard of honour, and were then given a 21-gun salute.

The official departure ceremony took place at Rotary Challenger Park, after which William and Kate proceeded to the airport. The couple landed in California around 4 p.m. local time.

Just before stepping on the plane, the Duke and Duchess were presented with flowers by 81-year-old Frances Miller, an Alberta woman who had missed an opportunity to greet Queen Elizabeth and King George during their tour of Canada back in 1939.

U.S. visit

Unlike their nine-day trip to Canada, during which they mingled with the locals and took some time to take in the sights by themselves, the royal couple will primarily focus on business in their brief California excursion.

Reporting from Hollywood, NBC correspondent Tracie Potts said that, even though the U.S. does not have the same historical affinity for the royals as Canada, the level of interest in the couple's visit is nevertheless very high.

"I've heard a lot of people say, 'We really don't have this here, I just really want to see them, and see what they look like,'" Potts told CTV News Channel Friday.

Compared with their Canadian tour, there may not be the same level of public access during the couple's U.S. swing however.

Instead of trips to the beach or Disneyland, the Duke and Duchess will be promoting British interests in the U.S. by attending such events as a British Academy of Film and Television Arts (BAFTA) dinner honouring 42 young British filmmakers.

They'll be staying at the home of the British consul-general in the Los Angeles neighbourhood of Hancock Park while they attend events including a charity polo match in Santa Barbara, before heading home on Sunday.

Canada 'exceeded expectations'

At a reception Thursday night in Calgary, William said that his and Kate's tour of Canada has "exceeded all their expectations." He said he and Kate will long remember the many young Canadians they've met, and promised they would return in the future.

Decked out in a white cowboy hat, western shirt and jeans, the prince told the reception: "In 1939 my great grandmother, Queen Elizabeth the Queen Mother, said of her first tour of Canada with her husband, King George VI: 'Canada made us.' Catherine and I now know very well what she meant."

"We have seen how geographical diversity is matched by the diversity of the people we have met: Anglophone and Francophone, First Nation and new immigrant," he said.

Prime Minister Stephen Harper also toasted the couple and their successful tour.

"I say, we haven't seen a love-in like that since the first visit of the Beatles," he said of the couple's reception throughout Canada

Harper also announced a Parks Canada youth ambassador program named after the couple. The program will allow two young people to tour Canada's parks and promote their experiences over social media.

During their time in Calgary, William and Kate took in some rodeo demonstrations, including bull riding and the chuckwagon racing. They were also presented with white cowboy hats -- a ceremony similar to receiving the keys to the city. The couple also took in a tour of a high-tech laboratory at the University of Calgary and met a young cancer patient.

With files from CTV News Calgary and The Canadian Press