The Prince and Princess of Wales have arrived in Boston at the start of their three-day trip, with Prince William paying a touching tribute to his late grandmother the Queen.
After touching down at Boston's Logan Airport on a British Airways flight from London, William and Kate were greeted by Governor of Massachusetts Charlie Baker, First Lady of Massachusetts Lauren Baker and Lt Gov Karyn Polito.
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In a statement, the Prince said: "Catherine and I are delighted to be back in the United States and are extremely grateful to Governor Baker and The First Lady of Massachusetts for their warm welcome into Boston.
"On this, our first overseas visit since the death of my grandmother, I would like to thank the people of Massachusetts and particularly of Boston for their many tributes paid to the late Queen.
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"She remembered her 1976 bicentennial visit with great fondness. My grandmother was one of life's optimists. And so am I. That is why last year we launched the Earthshot Prize with the ambition to create a truly global platform to inspire hope and urgent optimism as we look to save the future of our planet.
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"To the people of Boston, thank you. I’m so grateful to you for allowing us to host the second year of the Earthshot Prize in your great city. Catherine and I can’t wait to meet many of you in the days ahead."
The royals during the Queen's Jubilee
In line with the environmentally-friendly theme of their visit for the Earthshot Prize, the royal couple flew commercial and are being driven around in a hybrid Range Rover.
Among their entourage are two private secretaries, two assistant private secretaries and staff from their communications team.
The trip will focus chiefly on the Earthshot Prize and the ceremony itself will be as green as possible. Guests have been asked to wear sustainable outfits that could be vintage, re-used or recycled.
William and Kate took a commercial flight
More than three acres of plants will decorate the green carpet and show set, including New England-grown evergreen and deciduous trees that are native and grown locally.
All the flowers have been grown within 100 miles of the MGM music hall where the show will take place and all the plants will be donated to local community-based organisations afterwards.
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The show lighting will be LED battery-operated and the same green carpet used for last Year's ceremony at Alexandra Palace will be used in Boston. Makeup used will be mostly vegan and certified cruelty-free, the food served will all be plant-based and there will be no single-use plastics.