Daylight saving time is a popular practice in the United States, where clocks move forward 1 hour on the second Sunday in March and fall back on the first Sunday in November. In the late 1940s, the use of daylight saving time, also known as fast time, became popular in cities. Indiana is officially in the Central Time Zone, but some communities choose to follow fast time throughout the year, essentially aligning with the Eastern Time Zone. In an effort to settle the debate, the Indiana General Assembly passed a bill to put all of Indiana in Central Standard Time and ban daylight saving time.
However, several counties in eastern Indiana (Ohio and Dearborn counties, near Cincinnati; and Floyd, Clark and Harrison counties, near Louisville) chose to observe daylight saving time unofficially, despite Indiana statute. In 2006, Indiana enacted a statute officially placing northwest and southwest Indiana in the Central Time Zone, in observance of daylight saving time, and the rest of the state in Eastern Standard Time throughout the year. Supporters of daylight saving time 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. On the other hand, detractors of daylight saving time say scientific studies evaluating the impact of the time policy change on daylight saving time in Indiana have identified a significant increase in energy use and electricity spending by Indiana households.
In 1985, the Indiana General Assembly asked the USDOT to move five counties in southwest Indiana (Posey, Vanderburgh, Warrick, Spencer and Gibson) from the central time zone to the eastern time zone. Today, most of Indiana follows Central Standard Time year-round while some counties observe Daylight Saving Time. The debate over whether or not all of Indiana should follow Daylight Saving Time continues.