The shooting occurred at about 10 p.m. in the inbound lanes of I-57 near Cicero Avenue. Police said the 55-year-old woman was on her way to work and driving a Chevy Malibu when she was shot multiple times before crashing into the median.
The woman was pronounced dead at the scene, police said. The victim was identified by family as Tamara Clayton.
The USPS said Clayton was a mail carrier at the Chicago International Military Service Center facility and had been with the Postal Service since 1993.
"The Postal Service is deeply saddened on hearing of this tragedy and share our thoughts and prayers with the family," a USPS spokesperson said in a statement.
RELATED: 3 injured, including 2 boys, in I-57 shooting in Calumet Park
Several shell casings were found and all inbound lanes of the expressway were closed for an investigation until after midnight. No suspects are in custody, police said.
Anyone with information on the shooting is asked to contact ISP at 847-294-4400.
Earlier Monday, three people, including two young boys, 12 and 15-years-old, were wounded in another shooting on I-57 near Calumet Park. A 38-year-old man remains in critical condition.
It happened after 4 p.m. in the northbound lanes at 127th Street. All lanes had to be shut down during the evening rush for the investigation.