The Prince of Wales and his wife the Duchess of Cornwall are to pay their second joint visit to the US shortly.
The Royal couple visited the US in November 2005
Charles and Camilla will spend two days in Philadelphia and New York on 27 and 28 January, Clarence House said.
The prince will receive the Harvard Club's Global Environmental Citizen Award in New York from last year's recipient, Al Gore.
The couple's first overseas tour together was also to the US, in November 2005.
Clarence House described the main themes of this month's visit as youth development, urban regeneration and environmental conservation.
"The prince's visit will emphasize the importance which the UK Government places on climate change as a key international priority," a spokeswoman said.
On their November 2005 trip, the couple visited hurricane-hit New Orleans and Ground Zero in New York.