LESTER HOLT, co-host: After a bit of a reprieve, gas prices may be going up again. Conflicts in Nigeria and Iran have crude oil prices on the rise, climbing above the $60 a barrel mark for the first time in more than a month. But before you complain, consider where the price of gas comes from. Author Lisa Margonelli traveled more than 100,000 miles to find out, and the journey is documented in her book "Oil On The Brain: Adventures From the Pump to the Pipeline."

And, Lisa, good morning. Thanks for being here.

Ms. LISA MARGONELLI ("Oil On The Brain"): Good morning.

HOLT: We're all dying to know where the price of gas comes from, but I'm also dying to know why you did this trip? I mean, journey or obsession?

Ms. MARGONELLI: Obsession. Both, actually. I was--I started hanging out at a local gas station and just--I really wanted to get close to the people and the machines and the economies that make our lifestyle possible. So I started at the gas station, hung out all along the way with truckers, at the refinery, on a drilling rig in Texas, and then went abroad to places like Venezuela and Iran and Nigeria, the places where the prices are being made.

HOLT: Right. Most of us just pull up to the pump, we grumble about the price, we fill it up, we figure somebody's lining their pockets, but we don't give it much more thought. What did you find out about where that price comes from that we pay?

Ms. MARGONELLI: Well, the big changes in price come from overseas, like you said, in Nigeria and Iran. There, the prices--the crude oil prices bounce up and down because of little conflicts overseas.

HOLT: Why is it that something will happen overseas today and tomorrow the guy on the corner has raised it 4 cents a gallon. Clearly, he hasn't taken a shipment in the last couple of hours.

Ms. MARGONELLI: No, but he has to price his gasoline based on the cost of his next tank. He has to be able to pay for his next tank of gas...

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