HOUSTON (MCT) — The largest drought in more than half a century strengthened its grip on the United States this week, particularly in the Midwest and High Plains farming states, according to the latest U.S. Drought Monitor report released Thursday.

More than 70 percent of the Midwest was in some stage of drought this week, up from 63 percent last week, according to the report by climate experts. Half of the Midwest, which produces about 75 percent of the country’s corn and soybean crop, was in severe to exceptional drought, up from about a third last week.