In the late 1940s, the use of daylight saving time, 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 themselves with the Eastern time zone. The state of Indiana is located in the Eastern time zone of the United States. Eastern Standard Time (EST) is 5 hours behind Greenwich Mean Time (GMT), but there are exceptions and this has changed over time.
In Indiana, 80 counties are in the Eastern Time Zone, while 12 counties in the Evansville and Gary metropolitan areas of Indiana are in the Central Time Zone.