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SCOTT JAGOW: The typical Mexican family of four eats more than two pounds of tortillas a day. That's a lot of tortillas. The price of tortillas has tripled in recent months along with the price of corn, so you can understand why Mexicans are taking to the streets today in protest. From the Americas Desk at WLRN, Dan Grech reports.

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DAN GRECH: Why have tortilla prices spiked?

Economist William M. Edwards at Iowa State University points to the growing demand for ethanol as an alternative fuel.

WILLIAM M. EDWARDS: A larger number of plants coming on line and finally reaching the point where there was competition of corn for ethanol versus corn for livestock feed and other uses.

But many low-income Mexicans believe tortilla makers are hoarding corn to raise prices.

One company, Grupo Gruma, controls as much as 80 percent of the country's market for tortilla flour.

Mexican President Felipe Calderon recently stepped in. Calderon capped tortilla prices, but the caps are voluntary and today's protestors say they still leave prices too high.

I'm Dan Grech for Marketplace.