A weekly tracker of the nation's worst drought in decades says parched conditions continue easing in key Midwest states as farmers step up their corn harvests. The U.S. Drought Monitor update released Thursday says recent rainfall that benefited portions of the Corn Belt came too late to help already damaged corn crops, but may plump up still-maturing soybeans. The report shows about one-fifth of the U.S. remains in the two worst categories of drought: extreme and exceptional.