ABC, with "pardonable exaggeration", billed the third presidential debate as "the most technically complicated broadcast in history". While bold, that claim seems to be corroborated by newspaper articles describing the production setup which were published in the run-up to and aftermath of the debate.

Three studios were used for the debate: one in Los Angeles for Nixon, one in New York for Kennedy, and another in Los Angeles for the moderator and panel. The decision to place the panel at a third location was made out of fairness, which was a running theme throughout the preparation for the production - the backdrops of Kennedy and Nixon's respective studios were literally cut from the same bolt of cloth, and the same bucket of paint was used to paint Kennedy's desk before being flown to Los Angeles to paint Nixon's!

It's important to note that while Nixon and Kennedy could see and hear each other, it wasn't what we would think of as a videoconference: each man was simply on a live television feed broadcast to the other.

Nine cameras were used, three at each studio. All nine television feeds went to producer Marshall Diskin in Hollywood, who chose which picture to show at any given time. The chosen feed would then be transmitted to Chicago before being carried to local networks and stations. This meant, as The Washington Post Times-Herald noted, that "the picture of Sen. Kennedy will travel across the continent... thus, 6000 coaxial miles will have been covered before people in New York get the signal". ABC stated that over 500 production staff were employed in the broadcast.

Interestingly, while the debate opened with a now-familiar split screen shot that appeared to show Nixon and Kennedy standing side-by-side, Diskin opted not to use that shot for the rest of the debate on the grounds that doing so would be "distracting". That meant no reaction shots of the sort that we now associate with Presidential debates.

Combined with the lack of interruptions and opening statements, tracking the action was rather straightforward - much more so than today. An examination of the footage of the debate shows that the feed only switched about 40 times in 60 minutes, and the transcript shows the two candidates speaking in long, uninterrupted paragraphs.

While the format was novel, the debate proceeded relatively smoothly. Polling data suggested that this was Nixon's strongest debate, a finding that was attributed to the lack of reaction shots - Nixon was depicted wiping his face in a reaction shot in the first debate despite requesting that no reaction shots be taken - as well as his stronger performance in the substance of the debate, which largely centered on foreign policy in general the Taiwanese islands of Quemoy and Matsu in particular.

In short, the third debate of 1960 was technologically possible because existing live television technology was employed at large scale with a relatively simple format that eased the demands of filming and combining multiple feeds.

Sources:

Laurent, Lawrence. “ABC Facilities Tonight Just as 'Equal' As Can Be.” The Washington Post Times Herald, 13 Oct. 1960, p. B6.

Schroeder, Alan. Presidential Debates: Fifty Years of High-Risk TV. Columbia University Press, 2008.

Shanley, John P. “Studios on Both Coasts Set Up To Handle Third in TV Debates.” New York Times, 14 Oct. 1960, pp. 22.