For the second year in a row, one of Andy Granatelli's STP Turbine-powered machines was leading late in the race, but once again, it failed within sight of victory.

[3][4][5][6] On lap 174, Lloyd Ruby's engine misfired allowing Joe Leonard to take the lead in the Lotus 56 Turbine.

Unser, in the venerable piston-powered Offenhauser, inherited the lead and won the race despite gear linkage trouble.

With 9.25 inches (23.5 cm) of precipitation in the Indianapolis area in May, the 1968 race featured the wettest month on record for the Indy 500.

This was the most recent Indy 500 scheduled for Thursday; the Uniform Monday Holiday Act was implemented in 1971 and Memorial Day became a three-day weekend (Saturday–Monday) every year.

Most of Bump Day (May 26) was rained out, and the track closed due to darkness with the field not yet filled to 33 cars.

* Includes days where trackactivity was significantlylimited due to rain The 1968 Indianapolis 500 was the second and ultimately the final year of participation by the controversial STP Granatelli Turbine machines.

Later, his STP Lotus 56 teammate Joe Leonard in #60 won the pole position with a four-lap average speed of 171.559 mph (276.1 km/h).

At 5:45 p.m., the track was finally opened for qualifications, and Jochen Rindt was the lone qualifier at 164.144 mph (264.2 km/h), while Denny Hulme waved off as the 6 o'clock gun went off.

At that time, officials deemed the conditions unsafe due to darkness, and postponed the remainder of qualifying until Monday morning.

At the drop of the green flag, Joe Leonard in the #60 STP Turbine took the lead, with Bobby Unser in second and Roger McCluskey up to third at the end of lap one.

On the restart, Bobby Unser took the lead, blowing by Joe Leonard, showing the traditional piston-powered engines were still a match for the powerful turbines.

When Bobby Unser made his last pit stop on lap 166, his gearshift linkage was broken, and the car was stuck in high gear.

As he slowly left his pit, struggling to accelerate back to racing speed, both Leonard and Ruby passed him.

For a brief moment, a controversy started brewing as Art Pollard (teammate to Joe Leonard), who was a couple laps down, was not keeping up with the caution pace.

Officials allowed the top five cars to finish the full 500 miles, then flagged the rest of the field off the track.

Graham Hill ran in the top five, but complained that he lacked speed down the long straights, and was running 4th when he wrecked.

Art Pollard, in the third Turbine, spent most of the day in the top ten before the car quit, but was never really a factor for the win.

The broadcast was carried by over 900 affiliates including 761[16] in the United States, Armed Forces Network, the CBC, and reached New Zealand and Australia for the first time.

Indiana Senator Vance Hartke visited the booth, escorting a delegation that included Secretary of Transportation Alan Boyd, FCC chairman Rosel H. Hyde, Utah Senator Frank Moss, and Jack Kauffmann (The Washington Star).

Jim McKay anchored the broadcast with Rodger Ward as analyst, and Chris Economaki as a pit reporter..

The race was shown live on MCA closed-circuit television in approximately 175 theaters across the United States.