According to the National Weather Service in Norman, Okla., the tornado, which struck the area near El Reno, Okla., was the widest on record at 2.6 miles.
The NWS also upgraded the intensity of the storm to EF5, which is the strongest level a tornado can reach.
The tornado was on the ground for 16.2 miles, during May 31, 2013.
The old record width for a tornado was the F-4 Wilber-Hallam, Neb., tornado on May 22, 2004, at 2.5 miles wide.
The tornado which struck near El Reno was double the width of the storm which hit Moore, Okla., on May 20, 2013.