Highlights from the 55th running of the Indianapolis 500

FILE - In this May 29, 1971, file photo, people fall off a camera stand after the stand was hit by the pace car driven by local Indianapolis-area Dodge dealer Eldon Palmer at the start of the Indianapolis 500 auto race at Indianaolis Motor Speedway in Indianapolis, Ind. (Frank Hanes/Chicago Today via AP, File) MANDATORY CREDIT CHICAGO TRIBUNE; CHICAGO SUN-TIMES OUT; DAILY HERALD OUT; NORTHWEST HERALD OUT; THE HERALD-NEWS OUT; DAILY CHRONICLE OUT; THE TIMES OF NORTHWEST INDIANA OUT; TV OUT; MAGS OUT; NO SALES (The Associated Press)

FILE - In this May 29, 1971 file photo, Al Unser gestures as he takes the checkered flag in his Johnny Lightning Special to win the 55th running of the Indianapolis 500 auto race at Indianapolis Motor Speedway in Indianapolis, Ind. (AP Photo/File) (The Associated Press)

FILE - In this May 29, 1971 file photo, Gordon Johncock climbs a third turn fence after climbing from his wrecked racer after a multi-car wreck during the Indianapolis 500 auto race at Indianapolis Motor Speedway in Indianapolis, Ind. Johnny Rutherford (18) passes the wreckage in the foreground. (AP Photo/Gene Herrick, File) (The Associated Press)

RACE: 55th Indianapolis 500

DATE: May 29, 1971

WINNER: Al Unser Sr.

AVERAGE SPEED: 157.735 mph

WHAT HAPPENED: Unser won for the second consecutive year and became the only driver to win on his birthday. He was the first winner to celebrate in the relocated victory lane, which now sported black-and-white checkered ramps and was in the "horseshoe" area near the start/finish line.

NOTABLE: An Indianapolis-area car dealer was the driver of the pace car, but he lost control of the Dodge Challenger at the south end of the pits at the start of the race. The car crashed into a photographers' stand, injuring 29 people.