[3][4][5] Al Unser, Sr. dominated the race, winning the pole position and leading 190 laps (of 200) en route to victory.

For the first time in Indy history, the total prize fund topped a million dollars.

This was the final 500 in which the winner celebrated in the old Victory Lane at the south end of the pits; it was relocated nearer the finish line for 1971.

However, despite a brief rain delay on race morning, the full 500 miles was completed Saturday, and Sunday was not needed.

The Uniform Monday Holiday Act would take effect in 1971, and for 1971 and 1972, the race would be scheduled for the Saturday of Memorial Day weekend.

[7] * Includes days where trackactivity was significantlylimited due to rain Al Unser, Sr. set the fastest speed during practice, with a lap of 171.233 mph.

Unser led the speed chart on five of the practice days, and was the only driver to crack the 170 mph barrier during the first two weeks.

On Monday May 11, defending race winner Mario Andretti spun and wrecked in turn four.

A few cars (namely Lloyd Ruby, Gary Bettenhausen, and Peter Revson) were still waiting in line when the rains came.

USAC officials closed the track for the day, and those cars were deemed ineligible for the pole round.

In subsequent years, the rules would be changed to allow all cars in the original qualifying draw order at least one chance to make an attempt during the pole round, regardless if it extended into an additional calendar day due to rain.

Peter Revson (167.942 mph) was the 9th-fastest car in the field, but lined up 18th due to being a second day qualifier.

[8] The incident drew the ire of the team, as they felt the officials cost them a chance to be the day's fastest qualifier (for having run the extra laps).

Jigger Sirois, infamous for missing the 1969 race, fell far short in Jack Adam's Turbine car.

Suddenly, Jim Malloy on the outside of the third row, suffered a rear suspension failure, and smacked the outside wall.

Under the caution, Mario Andretti was forced to make an unscheduled pit stop to repair loose bodywork.

As the race passed the 100-mile mark, Al Unser, Sr. led, with Johnny Rutherford running second, and A. J. Foyt and Lloyd Ruby battling for third.

Mario Andretti once again had to make an unscheduled pit stop, this time to change the right rear tire.

On lap 172, Roger McCluskey (driving for Kenyon), spun going into turn three, and crashed hard into the outside wall.

Unser's crew gave him the "E-Z" sign on his chalkboard, and both Mark Donohue and A. J. Foyt got their lap back.

The broadcast was carried by over 1,000 affiliates in all fifty states, AFN, the CBC, and reached locations such as Vietnam and had four foreign language translations.

Among the celebrity interviews Sid Collins conducted in the booth were Edie Adams, Dennis Hulme, Billy Shaw, Chris Economaki (ABC Sports), Larry Bisceglia, Sam Hanks, Pete DePaolo, Bill Holland, Senator Vance Hartke, Tony Hulman, Duke Nalon, Johnnie Parsons, and J. C. Agajanian.

Astronaut Pete Conrad, who was a fellow passenger with Tony Hulman in the pace car for the second year in a row, was also interviewed during the pre-race coverage.

Jim McKay anchored the broadcast with Rodger Ward and Chris Economaki as analysts.

For the final time, the race was shown live on MCA closed-circuit television in numerous theaters across the United States.