It comes as Hillingdon Council has vowed to oppose the airport's expansion after a Labour assembly member was photographed at a 'pro-Heathrow third runway' event.
'Make the right choice'
Heathrow's CEO, John Holland-Kaye, said: “Council leaders from across the country recognise expansion at Heathrow will benefit their local economy by creating skilled jobs and connecting exporters to growing markets overseas.
“Their support is further evidence that the next Prime Minister has the opportunity to make the right choice in the whole of Britain's interest by expanding Heathrow.”
A recent poll of MPs showed that two thirds were in favour of expanding the west London airport.
Heathrow expansion has also been backed by the MPs for Ealing North, Stephen Pound, and Ealing and Southall, Virendra Sharma.
A decision on airport expansion has been delayed until October, after a new Prime Minister in place.
'Uncertain economic times'
The letter says: “In uncertain economic times, it is undeniable that investment in Britain's infrastructure is even more important to support growth across the country.
“We are an island nation and so it is our airports that connect many of our exporters and their goods to growing markets overseas and are the first impression for tourists, students and investors coming to Britain.”
It goes on to say that the country's airports contribute £50billion a year to national growth and supports 1million jobs.
The letter ends: “This was their blueprint and it is now time to make a bold decision and put it into action.
“It's time to make the right choice and expand Heathrow.”