IndyCar will introduce three-wide starts for this weekend's race at Pocono and for the 2013 season finale at Fontana on October 19.
The two venues, along with the Indianapolis 500, comprise this year's revived Triple Crown, for which a $1 million bonus is on offer for winning all three, or $250,000 for triumphing in two of the events.
Three-wide grids have been run at Indianapolis since 1921, but only sporadically at other venues, Pocono among them.
IndyCar race director Beaux Barfield said track analysis has proved both venues are capable of hosting three-wide starts. Both Pocono (73 feet) and Fontana (53 feet) are wider than Indianapolis at the start.
"After having the opportunity to test at Pocono and a successful event at Auto Club Speedway last season, we were able to analyze track data and compare to our current start procedure for the Indianapolis 500," Barfield said.
"Given the speeds of our starts, the location of accelerations zones, the spacing between rows and the length of the frontstraights at each track, we have decided to move forward with a three-wide lineup for the initial starts."
All restarts at Pocono and Fontana will be conducted in single-file.
The Triple Crown last ran in 1989, when it comprised Indianapolis, Pocono and Michigan.