Kennedy and Nixon before the First Televised Debate, Chicago, 26 September 1960
The two candidates photographed at WBBM-TV in Chicago shortly before the first televised presidential debate. About seventy million people watched. The often-repeated claim that radio listeners thought Nixon won rests on one small, poorly documented survey and should be treated with care.
What the 1960 debates changed is not in dispute even where the radio anecdote is. For the first time a national audience saw the candidates side by side, unmediated by party organisation or friendly newspapers, and judged them partly on how they looked doing it. Campaigning afterwards was rebuilt around that fact: television time became the largest line in the budget, and the skills that won elections shifted accordingly. See television, mass politics and the 1960 election.
Public domain — source (Wikimedia Commons). Free to reuse under the stated licence.