The station is 50kW broadcasting from a tower smack dab on the Illinois/Indiana border, like David said.
The towns are Burnham, Il. and Hammond, In.
Its COL is Hammond.
It has an excellent signal through all of southern Chicago, the south suburbs and northwest Indiana.
Where it has problems is downtown, north side, northwest suburbs and west suburbs from about Aurora out west, due to adjacent 92.5 in Dekalb.
That said, there is a big difference with a car radio and say a portable fm ipod or mp3.
Downtown and Northside of the city forget it unless its a car, there is too much rf from the Willis and Hancock to get a good signal.
There is not a lot they could do to change it. They can't move west due to 92.5 can't go north or downtown because of 92.7 just north of Arlington Heights.
On the plus side they do have one of the best signals on the south side and south suburbs, they come in very well even on cheap clock radios.