An image from NASA shows the impact of the drought across the United States.

 

The extent of damage to crops is shown in this vegetation anomaly map based on data from the NASA Terra satellite. The map contrasts plant health in the central United States between June 25 and July 10, 2012, against the average conditions between 2002 and 2012. Brown areas show where plant growth was less vigorous than normal; cream colors depict normal levels of growth; and green indicates abnormally lush vegetation. Data was not available in the gray areas due to snow or cloud cover. The image is based on the Normalized Difference Vegetation Index (NDVI), a measure of how much plant leaves absorb visible light and reflect infrared light. Drought-stressed vegetation reflects more visible light and less infrared than healthy vegetation.

The most severe damage to crops appears to be centered on Missouri, Arkansas, Oklahoma, Texas, Kansas, Nebraska, and South Dakota. Crops in much of the upper Midwest—southern Wisconsin, Michigan, Indiana, southern Illinois, western Kentucky, and western Tennessee—also show signs of strain.  The drought has been less severe in Iowa, a key corn-growing state.