As of 2015, the unofficial start time of the Indianapolis 500 is at 12:13 p.m. The unofficial start time of the race begins with the traditional singing of "Back Home Again in Indiana," followed by the command being given at 12:15 p.m. for drivers to start their engines.
Once the command is given for drivers to start their engines, they run several pace laps before the green flag is waived at 12:21 p.m., signaling the start of the race.
The Indianapolis 500 on May 24, 2015 marks the 99th running of the event known as the greatest spectacle in racing. Held at the Indianapolis Motor Speedway, the race covers 500 miles on a 2.5-mile oval track and consists of 200 laps.