Kate and William's US expansion as Harry and Meghan popularity plummets

The Royal Foundation, responsible for the couple's charity work, aims to use research and long-term partnerships to have positive and measurable impacts on social challenges.

Campaigns launched by the organisation include Prince William's environmental 'Earthshot Prize' and Princess Catherine's early childhood initiative, 'Shaping Us'.

It is thought The Royal Foundation registered to protect its name in the United States to reflect William and Catherine's new Prince and Princess of Wales titles.

However, the future King and Queen's organisation is understood to be leaving the door open for future charity initiatives in the United States of America.

WATCH: Prince William spent time in New York recently

The trademark covers "public awareness campaigns" and "charitable activities in the field of mental health", according to the application.

Also listed is "printed race numbers" suggesting the Prince and Princess could be thinking about some sort of sporting event, although it is understood there are currently no plans for this.

Last month, Prince William was publicly praised in New York by the city's former mayor, philanthropist and businessman, Michael R Bloomberg.

Mr Bloomberg quoted a Gallop poll which named The Prince of Wales as the number one public figure to unite America.

"The Prince has clearly won over Americans of all stripes", he said.

Continuing, Michael R Bloomberg joked: "America has not seen that kind of bipartisan consensus since 1776."

Meanwhile, the Prince's estranged brother, who moved to the United States in 2020 with his wife Meghan, has been experiencing a slump in popularity.

According to last month's survey for Newsweek, Prince Harry's popularity has dropped six points since June, and Meghan Markle's popularity was down eight points.

Kensington Palace has been contacted for comment.