That figure is up from 2012, in which the survey found that wedding guests spent an average of $329 on the big day.
It's even worse for bridal party members, who can expect to spend an average of $577 on bachelor/bachelorette parties and expensive attire, though only a third of bridesmaids planned to wear their dresses again.
So what caused the increase?
David Rabkin, American Express' senior vice president of consumer, explained that Americans "are a little less hesitant to go to their wallets," now that the economy is improving and "financial optimism is on the rise."
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