With weeks of soaring summertime temperatures and little rain, the United States is suffering through its worst drought since 1956.

Agriculture Secretary Tom Vilsack briefed President Barack Obama on the spread of the drought Wednesday, telling him 61 percent of the country's vast lands are now parched, with vital corn and soybean crops severely stunted.

Most of the country's drought-stricken states are in the southern half of the country. But agriculture officials said farmlands further north are now increasingly drying up as well.

The United States is the world's leading producer of corn and soybeans, two crops used to feed livestock and in food production. But Vilsack, once the governor of the key farmland state of Iowa in the central U.S., told reporters at the White House that the drought has sharply curtailed growth of the two crops.

“There's no question that this drought is having an impact on our crops. Seventy-eight percent of the corn crop is now in the area designated as drought-impacted, 77 percent of the soybeans that are being grown in this country (are) also impacted and also it involves other commodities as well. Thirty-eight percent of our corn crop as of today is rated as poor to very poor, 30 percent of our soybeans, poor to very poor, and this obviously will have an impact on the yields produced on individual farms.”

The agriculture secretary said the drought has led to markedly higher prices for corn and soybeans, pushing corn up to $7.88 a bushel, a 38 percent jump in recent weeks, while soybean prices have reached a four-year high.

However, Vilsack said U.S. consumers may not see higher prices for beef, poultry and pork in the short term because ranchers may reduce the size of their herds of animals sooner than normal, rather than pay the higher feedstock prices to keep raising them. That would tend to curtail grocery store meat prices for the moment, although prices could increase several months from now.

Still, he said the overall impact of the drought is hard to predict, in part because some isolated areas of rain and the use of drought-resistant seeds have helped crops grow well in some places. Even with the drought, he said the U.S. corn crop could be the country's third largest ever, in part because more farmlands were planted with corn this year.

Vilsack said Mr. Obama streamlined the process for declaring drought-stricken areas as eligible for government financial assistance and cut the interest rate on disaster loans.