Hundreds of people greeted him on Washington’s Capitol Hill when he attended an event promoting the HALO Trust, an anti-landmine charity he supports.
And when he was announced as a surprise guest at a White House tea reception honouring military mothers he received a standing ovation and more whoops of delight from US servicewomen and their children. He was a surprise guest whose attendance had been kept secret from the 170 invited mothers, grandmothers and youngsters.
Mrs Obama and Dr Jill Biden, the wife of Vice President Joe Biden, hosted the White House event in honour of military mothers.
It was part of their Joining Forces project, a nationwide initiative launched in 2011 to encourage Americans to support and provide opportunities for the military and their families.
Before Prince Harry was introduced to the military mothers he had joined their children who were making Mother’s Day goody bags in the White House’s state dining, filling them with bouquets of roses, edible salted dough jewellery and baked crisps.
With Mother’s Day traditionally held on the second Sunday of May in America, the children were busy at work. But The Prince soon joined in bending down to talk to the children and pulling faces and joking with the youngsters.
At one point Mrs Obama joked that the parents were getting “a couple of minutes of free babysitting”.
Earlier in the day Prince Harry was given a deafening welcome when he arrived at the Russell Senate Office building on Capitol Hill for a photographic exhibition highlighting the work of the Halo Trust.
He was joined by former presidential candidate Senator John McCain who stepped in as a replacement for his wife Cindy, a leading US anti-landmine campaigner, after she was taken ill.
The Prince has followed in the footsteps of his mother Diana, Princess of Wales by supporting the Halo Trust, founded in 1988, and this year the became Patron of its 25th anniversary appeal.
Prince Harry also visited Africa to promote the charity’s work travelling to Mozambique in 2010 where, under supervision, he detonated several mines and met people who had lost limbs to landmines.
Mr McCain, a former fighter pilot who was held hostage after being shot down in Vietnam, said: “He knew I had been shot down and I told him he was probably a much better pilot than me because he hadn’t been shot down.”
The tour will also take The Prince to New York where he will support the Great Campaign, a government initiative which promotes the UK around the world on the back of the success of the Diamond Jubilee and London 2012.
Prince Harry will also attend a baseball event in the Big Apple as he promotes a sports programme involving his Royal Foundation. On the final day Prince Harry will play in the Sentebale Polo Cup in aid of his Africa-based charity.