Every corn-producing state west of the Mississippi is suffering from some degree of drought:

http://www.drought.unl.edu/dm/monitor.html

This area produces nearly 60% of the US corn crop, led by Iowa, Nebraska, and southern Minnesota.  Most of the major corn growers east of the Mississipi (Illinois, Indiana, Ohio) appear to be better off.  Wisconsin is the exception; it is experiencing unusual drought in the north and central parts of the state, but less so in the south, where most of its corn is grown.