New York (CNNMoney) - From paying for a designer dress to renting a fancy limo, teens (and their parents) are shelling out hundreds or even thousands of dollars this prom season.

On average, families expect to spend $1,139 on prom this year - up roughly 40% from 2011's $807 average and a slight increase from last year, according to a Visa survey.

Families in the Northeast expect to pay the most, an average of $1,528, while Midwestern families were the most frugal, at an average of $722, according to the survey of more than 1,000 parents of prom-aged teens.

With traditions like debutante balls falling out of fashion and young people getting married later in life, prom has grown in importance and people are willing to spend more on the big night, said Kit Yarrow, a consumer research psychologist.

"Prom is the new wedding," Yarrow said. "I think that every society has to have a rite of passage into adulthood for young people, and prom has become that."

The increase in prom spending is also being driven by the popularity of photo-oriented sites like Facebook and Instagram, she said. Prom is "a post-able moment" which has heightened the pressure around appearances.

While parents still foot a majority of the bill, teens pay for about 41% of the costs, Visa's survey found.

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