So what happens to those parts of the country that never went on daylight savings time to begin with?
At least two states (Arizona and Hawaii) have never had DST. So do they have to have it now?
Indiana is messed up with time zones in general. While the
Standard Time Act put the state in the Central Time in 1918, it was inconsistently divided between Eastern and Central time zones in the early 60's. For the next couple of decades counties varied which time zone they observed. The entire state did not follow DST.
The argument for the two time zones is made for the counties in the far northwest and southwest corners of the state. The northwest counties proximity to the Chicago area and the southwest counties proximity to western half of Kentucky which also follows Central Time. The eastern half of Kentucky is Eastern Time.
In 2006, the US Department of Transportation finalized a rule that put the counties in Pulaski, Daviess, Dubois, Knox, Martin, Perry, and Pike on Central Time in April 2006 along with the entire state observing DST. Five of those counties- Daviess, Dubois, Knox, Martin, and Pike returned to Eastern Time in November 2007.
Right now, 80 of 92 counties use Eastern Time. There is a group that formed in 2009 that is arguing that Indiana should be in the Central Time zone as the state is geographically located in that time zone.