A lot of the trans-continental traffic that originates in the Los Angeles and Long Beach ports use what is called the "transcon" route to Chicago. The transcon route was the old Santa Fe freight mainline. If that traffic is headed to the East Coast, I know that BNSF cooperates with Norfolk Southern and CXST to run the trains through Illinois because you will see some unit trains on BNSF tracks (both the old Santa Fe and the old CB&Q) with NS or CSX engines helping to pull the train. But the fact that I see transcon trains in the Chicago area with NS power indicates that they are not diverted at Streeter, IL, to use a former NYC track that goes East to Indiana. Looking at a 1928 Railroad Atlas, I see this NYC line went to South Bend. Unfortunately, when I look at a current Indiana map, most of the line has been abandoned! I drew a blue line along the old NYC line that would have made a nice bypass of Chicago for all transcon-NS trains because NS's major classification yard is in Elkhart, which is east of South Bend.
BTW (By The Way), the reason the old NYC line goes as far east as it does is because of a coal-fired power plant a little northeast of Wheatfield, IN. Given that many coal-fired power plants are being converted to gas because the new shale fields have made gas cheaper and because it reduces the plant labor by half, you have to wonder how long that stretch of track is going to remain.
Some of the congestion problems in Chicago may disappear because the railroads may loose a lot of the trans-continental traffic when the larger Panama Canal opens