One story about the demographic changes in Chicago that I find underrepresented is the increase in downtown population. Historically, downtown Chicago's population was described as being like a volcano: empty in the middle and surrounded by great heights, then gradually decreasing to a shallow exterior. This is changing.
Via the New York Times
As you can see from this map the neighborhood of downtown Chicago adjacent to Grant Park increased population by over 300%. This neighborhood historically has had low population, hence the phenomenal growth. In fact much of the Loop has been sparely populated and only in the recent years has space been repurposed residential.
One can observe Chicago's demographic changes better on this map. Downtown and areas near downtown are populating. Some of the inner ring neighborhoods are depopulating. Many of these depopulating areas are heavy industrial zones, as we will see later.