Cellphone video captured a United States Postal Service truck going off-road in southwest Miami-Dade, speeding past traffic on the highway.
The video, which was posted on the Facebook page "Only in Dade," was captured by a driver sitting in traffic near Krome Avenue and SW 184.
A spokesperson with the USPS said they are currently reviewing the video.
"This is clearly unacceptable behavior that does not reflect the efforts of the thousands of professional, dedicated carriers in our workforce," said Debra J. Fetterly of the USPS South Florida District.