The Austin neighborhood on the far west side of Chicago and Oak Park, IL are contiguous neighbors. The border runs down the yellow stripe in the middle of Austin Boulevard.
According to this NYT map  of homicides in Chicago neighborhoods over the last 12 years:
Austin: More than 450 homicides have happened in this neighborhood in Chicago’s West Side, one of the city’s deadliest places
It must be the lack of gun control laws in Chicago.