Record petrol prices have triggered an unprecedented surge in the number of Americans using public transport, with traffic numbers for yesterday's Memorial Day, which opens the US summer vacation season, expected to be down by as much as 8 per cent.

With pump prices at about $3.75 (£1.90) a gallon, an increasing number of Americans have already been choosing to travel to work by train or bus.

Amtrak, the nationwide train service, said that while its number of passengers had risen 11 per cent last year to about 25 million, the fastest rate of growth had been among commuters using its Acela Express, which connects Boston with New York, Philadephia and Washington. The East Coast line saw passenger numbers up by as much as a fifth last year.

An Amtrak spokesman said: “We are attributing about half the rise to the cost of fuel. The rest is probably due to congestion and eroding conditions at airports.”

The American Automobile Association (AAA) yesterday said that while it will take a few days for final traffic figures for Memorial Day to be collated, it expects volume to have fallen. An AAA spokesman for New York State said that, based on survey data he had seen so far, he expects traffic to be down between 2 and 8 per cent compared with the same time last year. Meanwhile, over in the Midwest, Michigan has experienced two consecutive years of falling fuel tax receipts.

America's tourist industry is growing increasingly concerned about the impact that a reduction in car use could have on business.

Ellen Oppenheim, chief executive of the Reno-Sparks Convention & Visitors Authority in Nevada, said: “We have been watching all the travel studies and many people are going for shorter vacations than in the past and staying closer to home as well.”

She explained that some holiday companies were promoting rail packages in the San Francisco-Sacramento corridor and hotels in the area are responding with enticements, such as $50 petrol tokens for people booking two-night stays. Ms Oppenheim said: “We are trying to capitalise on the awareness of gas prices. We are looking at it and asking what should we be thinking about.”

The shift away from car travel has hit motor manufacturers at an already difficult time. This month, Chrysler tried to encourage drivers to trade in their old cars with a three-year pledge to cap the price of fuel.

The Detroit company said that anyone purchasing one of its new cars until June 2 would benefit from a reduced fuel bill, with the group fixing the price of petrol at $2.99 a gallon for the next three years.

Under the offer, new car owners would receive a card that would be presented at the filling station. The driver would pay the first $2.99 a gallon and Chrysler would pick up the rest until 2011. The actual saving would depend on the pump price over the period but the AAA estimated that, based on $3.61 per US gallon (0.83 Imperial gallon), someone buying a Chrysler PT Cruiser, which achieves about 21 miles to a US gallon in city driving, would benefit to the tune of $355 a year.

The New York AAA spokesman said: “This is just another incentive to buy gas-guzzling vehicles. Some of these car companies have about 150 days of unsold car production on their books. These guys are only just waking up to the fact that they need to develop new technologies for fuel-efficient cars. Toyota introduced the Prius in 1996; the rest of them are only just waking up to this.”

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