Eleven of the 33 starters were eliminated in a first-lap accident right after receiving the green flag on the main stretch.

Fellow first-time starter Graham Hill inherited the lead and led a total of 10 laps to win, the first rookie winner since 1927.

However, during post-race review, the scoring serials were settled later that evening, confirming Hill the race winner and Clark placing second.

For the second year in a row, the Wood Brothers from the NASCAR Grand National circuit were invited to work pit stops, this time for Dan Gurney.

[4] * Includes days where trackactivity was significantlylimited due to rain Three-year veteran Johnny Rutherford was injured in a serious crash on April 3 at Eldora, and was forced to sit out the 1966 race.

[5] The Mecom Racing Team was scheduled to field drivers Walt Hansgen, Rodger Ward, and Jackie Stewart.

Practice for the "Golden Anniversary 500" opened on Saturday April 30,[6] but cold temperatures and rainy weather for the first few days kept most cars off the track.

The confusion in the scoring led to a controversy, wherein second place Jim Clark's team thought they were the rightful winner.

Clark's team contended that he did not lose a significant amount of track position, and estimated that they were still one lap ahead of Graham Hill at the finish.

Colin Chapman and Andy Granatelli, the entrants of Clark's Lotus team, declined to file an official protest.

Alongside the controversy between Hill and Clark, fourth place Gordon Johncock is also theorized by some observers to have actually been the rightful winner of the race.

However, Johncock had suffered minor damage during the first lap accident, and restarted the race in the pit lane due to the crew changing the nose cone.

USAC officials did not score his first lap out of the pit lane, and he effectively ran all day carrying a one-lap penalty to the rest of the field.

The broadcast was scheduled for four and a half hours (including a 30-minute pre-race), but the red flag delay at the start extended it.

The broadcast was carried on over 725 affiliates in all 50 states, and 850 stations worldwide including shortwave transmissions from New York and Los Angeles, and XEVIP in Mexico City.

Through Armed Forces Network, the broadcast reached worldwide to locations including Vietnam, Japan, Korea, Saigon, Okinowa, Philippines, England, Spain, the Azores, Italy, France, Germany, Turkey, Greece, Pakistan, Morocco, Libya, Newfoundland, Iceland, Labrador, Greenland, and both the North and South poles.

Newcomer Doug Zink took the backstretch location, while second-year member Ron Carrell moved to turn three.

During this era, the radio network crew typically facilitated its own team of unofficial serial scorers to track the progress of the race.

[21] That allowed the scoring reports to be announced on-air faster than the official USAC scorekeepers could produce them from race control.

Guests in the booth during the red flag delay included Peter DePaolo, Cesar Romero, Johnnie Parsons, Wally Parks, Lucy Foyt, Phil Harris, General Howdy Wilcox, and Larry Bisceglia.

During the race, guests that stopped by included Walt Arfons, Frank Borman, Al Bloemker, Louis Meyer, Mickey Thompson, J. C. Agajanian, and Duke Nalon.

As a gesture celebrating the network's 15th anniversary, as well as the 50th running of the 500, guests were presented with a commemorative gold filled Zippo lighter.

One station, KXO in California, was noted and recognized as being one of the few original affiliates to carry the race all fifteen years since the network's inception.