In this July 13, 2012, photo, the Memphis Queen riverboat moves up the Mississippi River in Memphis, Tenn. A year after nearly record floods, the Mississippi River level has dropped so low that it's beginning to affect commercial operations. Port managers worry that their passages to the river could fill up with silt, and barge operators may have to lighten their loads. (AP Photo/Nikki Boertman)

Photos of the day - July 16, 2012