The Democratic National Convention is going on this week in Philadelphia, which brings to mind the conventions of 1948. Three major parties held their conventions in Philadelphia that year, and there was something new and special happening that year: the presence of TV cameras. It was the first year that the Republican and Democratic conventions were televised. There was a relatively small audience, since few people had TV sets, but the spectacle of the broadcast made the entire convention ritual different.
So, what, exactly, did viewers see? A lot of sweat, for one thing. The Philadelphia conventions that year were the last time political conventions were held in a venue that didn't have air-conditioning. And in video of Truman's speech at the convention, convention-goers are seen getting creative in how they fanned themselves, many using what appeared to be programs, mostly in vain.
On stage, things were considerably worse, mostly because of the lights. If the convention was to be televised, networks told convention organizers, the dais would need to be lit up. And, because of the primitive camera technology of 1948, that meant highly lit up. As a consequence, convention speakers, many of whom could be seen with visible sweat stains, probably had it the worst of anyone. (Their wives, sitting behind them, didn't have it much better.)
Of course, that changed everything forever. Not only did air conditioning debut at the next political conventions, there was also makeup, staging, and meticulous planning to make the television broadcast acceptable to viewers. Read about the clash of the old ways and the how television change politics at Atlas Obscura.