Prince Harry has become patron of the Walk Of America expedition, Kensington Palace announced.
The trek is the latest by armed forces charity Walking With The Wounded, and the prince will formally launch the epic hike in London on Wednesday April 11.
A team of six veterans from the US and the United Kingdom will walk 1,000 miles from the west to the east coast of America in 14 weeks this summer.
Starting in Los Angeles – Meghan Markle’s home – on June 2 and finishing in New York on September 6, the team will walk by some of America’s most famous cities and landmarks.
Expectations will be raised that Harry and his American bride-to-be will now choose the US as the destination for their first joint official overseas tour.
Kensington Palace said: “The Walk Of America will create a platform to tell the stories of wounded veterans and their individual journeys from injury to the present day, as well as encourage a wider conversation around veteran mental health.
“The expedition will also raise vital funds for veterans both sides of the Atlantic.”
In 2013, Harry took part in a gruelling trek to the South Pole in aid of the Walking With The Wounded charity, joining a team of injured British servicemen and women in the race against groups from the US and the Commonwealth.
Harry is not expected to take part in the Walk Of America.
At the launch next week, the prince will meet the three British team members and make a speech to formally launch the journey.
Kensington Palace said Ms Markle, who weds Harry on May 19 in Windsor, would not be joining the prince at the engagement.