US senator Bob Dole and broadcaster Sir David Frost will join actor Hanks in judging the competition, which aims to improve teenagers' knowledge of the Second World War.
The contest, revealed last week by The TES and launched on Tuesday by Education Secretary David Blunkett, will ask 14 to 16-year-olds to investigate the wartime relationship between America and Britain.
Philip Lader, the American ambassador to Britain who devised the contest, said:
"It is impossible for a history book to convey the depth and breadth of the British-American friendship."
Pupils will interview relatives and neighours or conduct local research in order to write a 1,000-word essay on Anglo-American relations.
Three winners will fly to Washington DC for a tour of the White House and Capitol Hill while 12 runners-up and the teachers who nominated them will win computers.
The competition is open to all pupils at state and independent schools in Years 10 and 11 in England and Wales, S4 and 5 in Scotland and Years 11 and 12 in Northern Ireland.
It is one of several schemes to commemorate the Second World War supported by Tom Hanks since his appearance in the film Saving Private Ryan
Schools who want to enter must register at the Department for Education and Employment website www.dfee.gov.ukusalliance by June 16. Essays must be submitted by July 21.