The silent, 8 mm color film is "the clearest, best film of Jackie in the motorcade," said Gary Mack, curator of the Sixth Floor Museum, which focuses on Kennedy's life and assassination.
The film shows a brief but clear glimpse of President Kennedy and his wife, Jacqueline, a few blocks from Dealey Plaza and roughly 90 seconds before the killing. Also visible is Secret Service agent Clint Hill riding on the back of the car. After the shots were fired, Hill jumped onto the car as it drove to the hospital.
The film ends with some footage the next day outside the Texas School Book Depository, the building from which assassin Lee Harvey Oswald fired the fatal shots.
"Because the speed of the motorcade was known to be between 12 and 15 miles per hour, I was able to figure out how far back in time it was from the assassination," Mack said.
Amateur photographer George Jefferies took the footage and held onto it for more than 40 years, Mack said. Jefferies mentioned it in a casual conversation with his son-in-law, Wayne Graham, and the two agreed to donate it to the museum.
At least 150,000 people lined the motorcade route, and Mack said he believes there are more film and photographs out there.
"I know there are pictures out here that have not surfaced," Mack said. "The museum is always on the lookout for pictures. The bottom line is don't throw anything away."