Their arrival was a lower key affair compared to the largely rapturous welcomes they received as they crisscrossed Canada. The royal couple had departed Calgary earlier Friday, having endeared themselves to Canadian crowds with a skillful mix of royal pomp and playful informality on their first official trip abroad since marrying.
Aside from a game of polo in the seaside city of Santa Barbara, much of the couple's three-day California visit will focus on business and not pleasure. Instead of trips to the famous Hollywood sign or Malibu's beaches, their itinerary includes some hefty fundraising for good causes, promoting U.S. investment in Britain and charitable work.
The newlyweds landed shortly before 4 p.m. local time (2300 GMT) in a Canadian military jet. The former Kate Middleton, who left Canada in a red satin and wool scarlet coat-dress by Catherine Walker, changed aboard the flight and emerged wearing a light-gray, knee-length dress with asymmetric draping at the shoulder. William wore a navy blue suit with a purple tie.
A small group of officials including California Gov. Jerry Brown and his wife Anne Gust, Los Angeles Mayor Antonio Villaraigosa and Britain's ambassador the U.S., Sir Nigel Sheinwald, greeted the couple at the airport.
Though Prince William has been to America before, it is Kate's first trip to the U.S. William's late mother, Princess Diana, who would have turned 50 this month, charmed Americans when she visited in the 1980s.
Authorities have put the paparazzi, known for their cutthroat tactics, on notice that aggressive actions will not be tolerated. Photographers were partly blamed for causing the Paris crash that killed Princess Diana in 1997.
The royal couple climbed into a black Range Rover and headed for their first event, a technology summit in Beverly Hills aimed at promoting U.S. investment in British tech firms.
Zoomed along by a California Highway Patrol motorcade, the duke and duchess avoided rush-hour traffic to the Beverly Hills summit by staying off the ever clogged West Los Angeles freeways.
The summit was set up to generate support for Tech City, London's answer to Silicon Valley. The area around the trendy Old Street part of east London is quickly becoming a hub for technology and software firms.
A small crowd of royal watchers gathered outside the hotel as the couple arrived but the duke and duchess did not stop to speak with them. Attendees stood and clapped as they entered the ballroom and sat on stage alongside other panelists.
Neither spoke during the discussion, though Kate smiled when the panelists mentioned that attendees were welcome to visit Tech City. At the end of the panel, the moderator asked if anyone wanted to talk. Kate nudged William, who shrugged off the opportunity.
Neil Stiles, president of Variety, which sponsored the event, accompanied the couple for brief demonstrations of technology on display at the expo, including the new tablet computer from HP and augmented reality applications from Qualcomm.
"They were delightful company," Stiles said. "They were relaxed, very comfortable in the environment. It was a lot to take in. They arrived at a conference that's been running all day on a very heavy business subject, and I thought they coped with it really well."
Britain's royal family has shown itself to be tech savvy in recent years and maintains accounts on several social media sites.
Residents in Hancock Park, the exclusive neighborhood that is home to the British consul general where William and Kate will stay, worked with police to create no-trespass notices for their homes. Any photographers standing on their driveways would be instantly arrested, though by late Friday the police said there had been no arrests.
On Saturday, the couple is traveling along the scenic Pacific coast from Los Angeles to the posh Santa Barbara Polo & Racquet Club for a charity polo game.
Later on, the duke and duchess will be guests of honor at a British Academy of Film and Television Arts dinner honoring 42 young British filmmakers and on Sunday, they will watch a dance at a nonprofit academy in the gritty Skid Row area downtown, then attend a job fair for U.S. servicemen and women transitioning to civilian life.
On Friday evening, the couple were honored at a reception at the consul general's home attended by such British notables as David Beckham and humorist Stephen Fry. Several news vans and bystanders were positioned across the street from the residence, which was blocked off by the Los Angeles Police Department, hoping for a peek at the couple.
In Canada, the newlyweds were cheered almost everywhere they went. They celebrated Canada Day with hundreds of thousands on Parliament Hill, did an impromptu walkabout in Quebec City, raced in dragon boats on bucolic Prince Edward Island and went canoeing in the wilds of the Northwest Territories.
A much talked about highlight was the race in Prince Edward Island when the prince's boat defeated Kate's. William's consoling hug and Kate's playful response she shoved the prince as if to push him into the water revealed their competitive, loving and fun side, and warmed Canadians' hearts.
There was a moment Thursday that almost amounted to a faux pas when the young prince and his bride appeared to snub their western Canadian host by not donning white cowboy hats upon arrival at airport, a time-honored Calgary tradition. But ruffled feathers were smoothed when the royal duo turned up for a rodeo show later in full western regalia, including the hats.
William said the nine day trip to Canada exceeded expectations and promised to return.
William's grandmother, Queen Elizabeth II, is Canada's titular head of state. Carolyn Harris, a royal historian with Queen's University, said the royal couple's visit would likely ensure the monarchy remains the head of state in Canada for years to come.
"The degree of popularity that the Duke and Duchess of Cambridge enjoy really shows that the institution really has a popular and viable future in Canada," Harris said.