An interesting historical note from INDIANA PARLEY: Time Zone History. Apparently back in the 30s, there was somewhat of a push in Chicago to get in the Eastern Time Zone. Actually, this passage suggests that Chicago was actually pushing for Hoosier Standard Time:
Beginning in October 1935, the Tribune pressed local officials to extend summer daylight saving time to a year-round basis, in effect placing Chicago in the eastern time zone[.]
As loyal readers are fully aware, year round Central Daylight Time is the same thing as year round Eastern Standard Time, which is what Indiana has had for the past 30+ years, but which will end this Spring.