Additional support from expectations of a slowdown in farmer selling as cash corn prices fall below $3 a bushel in some interior Midwest locations.
The US Department of Agriculture's weekly export sales report showed sales of 214,100 tonnes of old-crop corn, above trade expectations, and 647,500 tonnes of new-crop corn, below expectations for 700,000 to 1,100,000 tonnes.
Through its daily reporting system, the USDA said private exporters reported sales of 129,540 tonnes of US corn to Mexico, including 99,060 tonnes for 2016/17 delivery and 30,480 tonnes for 2017/18.
CME Group said it would lower the margins to trade CBOT corn futures, effective after Thursday's close.
China's National Grain Trade Center reported sales of 516,068 tonnes of corn at a state reserves auction, representing about 16 percent of the 3,199,717 tonnes available.
The CBOT reported 440 deliveries against the CBOT September futures contract.