· 2015 · 2016 · 2017 · 2018 · 2019 2020–2029 2020 · 2021 · 2022 Eras During the over-century long history of the Indianapolis 500 and Indianapolis Motor Speedway, numerous recognized eras have been established by historians, media, competitors, and fans. As the race follows the infancy of the automobile through the 20th century, and into the 21st century, sharp increases in technology, car design, and speed, have generally shaped the eras, which loosely follow decade patterns. Organizational changes and disputes, varying levels of popularity, increased media coverage, world wars, personalities, participants, traditions, famous races, and tragedies, have all been defining factors to establish the boundaries of the respective eras. Fisher Era From the opening of the track (1909) and the first 500 (1911), through 1927. Carl G. Fisher and partners envisioned a "proving ground" for the budding automobile industry. The very early years of the 500 saw the track in its original "proving ground" intent, but the competition soon became the primary focus. Numerous makes and models of local, national, and international car companies participated, with the cars more conforming to the original specifications of being essentially stripped-down passenger vehicles. Riding mechanics were the norm (with the noteworthy exception of Ray Harroun in 1911). The AAA Contest Board sanctioned the events at the Speedway, and the race ultimately became part of a National Championship of drivers. The discipline of Championship Car racing became a national sport, with the Indianapolis 500 as its marquee event. A maximum 33-car field was established, based on a 1919 mandate by AAA officials that of 400 feet of track per car. After World War I and during the Roaring Twenties, the formula quickly evolved into purpose-built racing machines. Small-block engines (91 cu. in) was the standard, riding mechanics were dropped, and the speeds quickly rose. Peter DePaolo became the first driver to average 100 mph for the 500 miles in 1925. Fisher sold his interests in the track in late 1927. Rickenbacker Era From 1928–1941. Eddie Rickenbacker purchased the Speedway in 1928, and ushered in a new era. Rules changes were abound, which included such things as the reinstatement of riding mechanics, time trials expanded to 10-lap runs (up from 4 laps), and engine rules which increased displacement and prohibited supercharging. After many years of small-block, purpose-built machines, the specifications once again reflected the very early years. The rule changes were in an