The history of official time zones in Indiana is a complex one, with a heated rural vs. city debate leading to the General Assembly passing a law in 1949 to put the entire state in Central Standard Time (CST) and ban Daylight Saving Time (DST). However, the law had no enforcement power and was largely ignored by communities that wanted to observe Eastern Standard Time (EST). In 1957, the Indiana General Assembly passed a law to make CST the state's official time zone, but allowed any community to switch to DST during the summer. This law was also largely ignored, and individual communities continued to observe their preferred time zone.
In 1961, the Indiana legislature repealed the 1957 law that made CST the official time of Indiana, allowing any community to observe DST. The Interstate Commerce Commission divided Indiana by the Central Time Zone and the Eastern Time Zone. However, neither the time zone line nor DST was observed uniformly. The United States Congress subsequently passed the Uniform Time Act of 1966 (Pub. L.), which required all states to decide on a single time zone for their entire state.
In response to this, Governor Roger D. Branigin asked the USDOT to put all of Indiana back in the central time zones a year later. After several hearings, USDOT chose to divide Indiana between the Central Time Zone and EST Zone. Six counties near Chicago and six counties near Evansville were placed in the central time zone respecting DST, while the rest of the state was placed in EST without observing DST. Several counties near Louisville and Cincinnati unofficially observed DST due to their proximity to major cities that observed it.
In 1968, several broadcasters filed a federal lawsuit to force USDOT to enforce DST in Indiana, which they won. As a result, USDOT was ordered to provide a plan for its enforcement. In 1972, Indiana General Assembly overturned a veto by Governor Whitcomb to place Indiana's northwest and southwest corners in CST during DST, and place the rest of the state in EST throughout the year.
Attitudes began to change in the 1990s when Indiana's complicated history of time zone situation was considered to prevent its economic growth. In 1991, Starke County asked USDOT to move it from CST to EST for the third time. This time, the petition was granted. Pulaski County returned to EST on March 11 when DST resumed. When Standard Time resumed on Nov. 3, all five Southwest Counties returned to EST.
The decades-long debate over Indiana's time zone remains controversial today. Some argue that the entire state should move to CST, while others would prefer that the state revert to non-observance of DST. Supporters of DST and a common time zone in Indiana often claim that Indiana should adopt the Eastern United States timing system to preserve interstate business with that region.
The confusion caused by having two different time zones has been highlighted by an episode of The West Wing in which presidential aides who were visiting Indiana were confused by its peculiarities when it came to weather.
The debate over what parts of Indiana are CST is ongoing and complex. While some counties have officially adopted CST with DST observance, others have chosen not to observe it or have unofficially adopted it due to their proximity to major cities that observe it. Ultimately, it is up to each individual county or community in Indiana as to whether or not they will observe CST with DST.