JEFFREY BROWN: Finally tonight, a dollar and a dream for millions of Americans.
Lotto fever, it seems, is sweeping the country.
MAN: That's it. Guys, you are all invited to my island after I win this. Thanks.
MAN: Which one is it with the most money?
WOMAN: The Mega Millions.
MAN: Give me one of those.
WOMAN: One sucker's going to win. Somebody's going to be a rich one, okay?
JEFFREY BROWN: The biggest jackpot in history, $640 million, is at stake in tonight's Mega Millions multistate lottery -- 42 states, Washington, D.C., and the Virgin Islands participate, 85 percent of the country.
Lines swelled today with hopefuls ready to plunk down a dollar for a chance at millions.
WOMAN: One, two, three, and good luck.
WOMAN: Thank you.
JEFFREY BROWN: Lottery officials said one million tickets an hour sold in the 48 hours after Tuesday's drawing failed to produce a winner.
GARY GRIEF, executive director, Texas State Lottery Commission: We have people coming out that have never bought a ticket before because they see this number and they think, gee, for just a dollar, I have a chance at a half-a-billion. It's hard not to take a chance on that.
MAN: Thirty-five, 40, 45, 50.
JEFFREY BROWN: The chance at big money, about $350 million after taxes if the prize is taken in one lump sum, had many who wouldn't otherwise play shelling out.
ANDREA SLONE, Store Manager: Your typical customers that would normally buy like $2 worth of tickets are now spending $20 to $50 and up to -- even they're coming in with $100 sleeves. So, I mean, even the people that don't play are tempted.
JEFFREY BROWN: Can the president be counted among the tempted?
JAY CARNEY, White House press secretary: No, but I'm going to run out and buy one.
JEFFREY BROWN: As did many others elsewhere in the nation's capital who dared to dream.
JASON DAVIS, lottery player: I'm buying 30 tickets, because if I'm going to play against astronomical odds, I figure why go in just halfway? If I were to win, I would probably pay off my debts, quit my job, and give all of my staff a million dollars.
WANDA BROWN, lottery player: I'm going to help some people and buy myself a nice house and a nice oceanfront property. Hopefully, I'm just the one that will win the money.
JEFFREY BROWN: But what are the real chances of winning? A lousy one in 176 million.
Some more reasonable odds, by comparison, getting hit by falling airplane parts, 17 times more likely. Or being hit by lightning, that's 50 times more likely to happen than winning tonight's big money.
But there are longer odds out there, for instance, the chance of being eaten by a shark is 280 million to one.
MAN: It's slim. It's slim, but I'm going to take that chance, like anybody else.
JEFFREY BROWN: So, with such long odds, why do so many play?
MIT Professor Andrew Lo studies the psychology of risk.
ANDREW LO, professor, Massachusetts Institute of Technology: We have an imagination, an extraordinarily refined imagination. And, as a result, we can conjure up all sorts of really interesting scenarios of what we might do with the money if we won, and how happy we would be, and so on and so forth.
And the very act of conjuring up these scenarios actually provides pleasure right now. So, in a way, what they're doing is buying the dream.
JEFFREY BROWN: Retailers have a stake, too. The store that sells the winning ticket could get up to $100,000, although foot traffic is the real boon.
RICK HARTMAN: Anybody that comes up so far since I have been here this morning, they come in for their coffee or whatever, they get their lottery tickets, too.
JEFFREY BROWN: The states that participate in the drawing also stand to benefit. If there's a winner in tonight's drawing, just over a third of that $640 million will go to the winning state in taxes.
In Georgia, for example, proceeds of the sale of tickets go to the HOPE Scholarship, which funds in-state college education for high-achieving students.
Still, it's definitely not all fun and games. In economically stressed areas, many people who have less money to play still do. Households earning under $13,000 per year spend about 9 percent of their income on lottery tickets, on average, according to a 2008 study from "The Journal of Risk and Uncertainty."
Of course, someone will win, but even that doesn't guarantee happiness.
ANDREW LO: When you win that kind of money, everybody knows that you have won that kind of money. So, all of a sudden, distant relatives, friends, people you never heard of are coming into your lives, asking for just a little bit of that money. And that creates an enormous amount of tension and ultimately unhappiness. So I think it's a mixed blessing.
JEFFREY BROWN: In the end, some will settle for small victories. . .
MAN: I won $9 today.
QUESTION: Back into the lottery or. . .
MAN: I'll take my cash.
JEFFREY BROWN: . . . while someone else will take about 71 million times more than that after a drawing tonight in Atlanta at 11:00 p.m.