After two straight months of slow but steady shrinkage, the drought ensnaring large swaths of the United States expanded this week.

The total share of land in drought increased by 1 percentage point this week, climbing to just over 50 percent, according to the latest U.S. Drought Monitor released this morning. Territory in each drought category increased this week with 16 percent of the country now in extreme drought or worse.

The expansion was driven by worsening conditions in California, Louisiana, Nevada, New Mexico, Oklahoma, Texas and Virginia. Exceptional drought -- the worst category -- crept into southern Kansas.

Nebraska, where the drought is centered, saw no change this week. The persistent drought in the Northern Plains is taking a toll on the winter wheat crop.

"Poor crop conditions on the Plains are driving the overall U.S. winter wheat crop to its lowest condition ratings since the records of this type began in 1986," said Brad Rippey, a meteorologist with the Department of Agriculture.

This year's drought, which covered 54.77 percent of the country at its Sept. 25 peak, is the largest in the Drought Monitor's 13-year history. The Palmer Drought Severity Index, which reaches back further into historical records, shows droughts in the 1950s and 1930s extended further than this year's.