Here's proof that investment math can be pretty simple: Fans keep turning out for NASCAR events, and International Speedway (NASDAQ:ISCA) keeps growing.

Led by strong attendance increases at a variety of events, higher TV revenue, and the rescheduling of a major California racing weekend into the first quarter, revenue climbed by more than 37% for the quarter. Even if you strip out the rescheduled California events, "same-track" revenue still grew by double digits.

As befits a company with good operating leverage, operating income climbed for the quarter by over 52%. Some increases in receivables and inventories, though, sent operating cash flow down a little bit, on a year-over-year basis.

While talking heads on sports channels like ESPN continue to debate whether NASCAR qualifies as a sport, people around the country continue to enthusiastically embrace it. Attendance and TV ratings are growing, and sponsors are increasingly eager to pay up to get their names and logos tied to racing events.

In the first quarter alone, International Speedway reached new agreements with companies like Checkers (NASDAQ:CHKR), ConAgra (NYSE:CAG), Goodyear (NYSE:GT), and XMSatellite Radio (NASDAQ:XMSR).

Looking ahead, you can see plenty of reasons to be optimistic. The company continues to move ahead with projects to build race facilities on Staten Island and the Pacific Northwest, and seat expansion continues to be an option at many tracks. What's more, the TV contract is soon coming up for renewal, and given the viewership trends for NASCAR, it is highly likely that the next contract will be quite favorable.

Although some investors may feel that these shares are a little too hot to touch, there's no arguing with the growth coming from racing in this country. What's more, the extremely close ties between NASCAR and International Speedway --they are run by the same family -- and the expense of building competing superspeedways gives this company an above-average economic moat.

Although the sort of growth NASCAR is seeing can't last forever, it's certainly making hay while the sun shines. Even for Fools who might not know the difference between a rub and a bump in racing, growth can be powerful stock fuel indeed.

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Fool contributor Stephen Simpson has no financial interest in any stocks mentioned (that means he's neither long nor short the shares). Although he's more of a Le Mans fan, he has been known to pull for NASCAR driver Matt Kenseth.