One item of contention I often read amongst the urbanist crowd is the issue of cars. Many people that enjoy city life and urbanism in general look at the automobile as a source of the decline of the American city, either directly or indirectly. While I can certainly see the issue cars present, especially in regards to parking, I find the issue to be rather complex.
Urban decline in America is approximately correlated with the permeation of the automobile in American culture. However it is also approximately correlated with the decline in manufacturing. It is also approximately correlated with desegregation. Since correlation is not necessarily causation I am reticent to place blame on one factor or even a host of factors.
Still the goal of reducing the scope of cars in city life is an interesting proposition. My own experiences have shown me that going carless in the 3rd largest city in America is rather difficult. But first, some background statistics.
Chicago is America's third largest city with a population around 2.7 million. It is the 4th most densely populated major city in America. It has America's second largest rapid transit system by number of stops and number of track miles. It is the third largest by ridership. However, it is 7th largest by rider density, or 6th if you consider the New York systems as one. New York, Philadelphia, Boston, Washington DC, and surprisingly Los Angeles all have a higher ridership per mile ratio.
Upon closer examination, the CTA's rapid transit lines look like a more condensed version of the Metra commuter rail system. The lines draw in from the edge of the city and converge downtown. So even if you are within walking distance of a CTA line, it most likely will only take you downtown. For many Chicagoans the most useful function of the L is to commute downtown for work.
Getting around the city without a car means using one of three modes of transportation: the train, a bus or cab, and walking. This can be very time consuming. It can also be expensive.
Here is a good example: If you want to go from a residence near the Clinton green line stop to a restaurant near the Ashland green line stop it is a 1.3 mile 25 minute walk but a mere 4 minute train ride. However that ride will cost you $2.25 each way, which is more expensive than driving - assuming that parking is free. Then again if you invest in a monthly unlimited pass then, depending on how often you use your card, this trip might be cheaper than driving.
I hope that this helps illustrate that there are many factors that influence the mode of transportation in Chicago. Travel time is a consideration, and car congestion is certainly a factor in Chicago. Price of traveling is another issue. Therefore the decision to walk, take a train, drive, take a bus, or take a cab is determined by a diverse criteria. Each element affects the other.
Going carless in Chicago can be rather difficult and isn't something I would attempt unless I lived downtown where the walkability is high and distance between train stations low.