Tourism officials in South Dakota and Iowa may have struck a goldmine: Free gasoline.

South Dakota announced its "Twenty Bucks for the Road" program last month, offering $20 gas vouchers to residents in 10 surrounding states (over 10,000 people have already cashed in). Iowa launched a smaller initiative this week, a sweepstakes in which Iowa visitors can register to win $50 gas cards. (But the state's only giving out 25 of them.)

This is brilliant tourism marketing: What could be more immediately effective at enticing people to visit your state than the promise of gratis gas? Of course, it means you're touting free petrol to draw tourists, instead of any actual attributes of your state. But whatever gets 'em across the border, I guess.

At any rate, it might not matter too much:  Fifty bucks'll get you, what, like two gallons?