Record-breaking heat is damaging crops across the country, and 15 states are under heat advisories Wednesday.

Many rivers are now at their lowest levels in years. The mighty Mississippi was 23 feet higher in Baton Rouge this time last year.

Forecasters say 80 percent of the country is unusually dry. They are calling it the largest natural disaster in U.S. history.

The governor of Missouri declared 114 counties a disaster area because of the drought.

"This has been the hottest, driest summer that I can remember. Now my father says that 1936 was drier, but then I was only 2 years old," farmer Charles Hurst said.

The extreme heat and lack of rain in the Midwest have hit corn, wheat, and soybean crops especially hard.

"You look at all of the Midwest that's facing this unprecedented drought, conditions like we haven't seen in nearly 120 years," Dr. Jon Hagler of the Missouri Department of Agriculture said.

The drought is likely to lead to higher food prices.