One word: Television.
Before Television, for the most part young people were clueless about current events, they didn’t read newspapers or listen to news on the radio.
Then with Television they could see what was going on, especially with Civil Rights, which up to that point was pretty much “Out of Sight, Out of Mind”. Then came the nightly coverage of Vietnam.
You could see what was going on that they wanted to tell you about. That's always a problem. As means of retrieving information expand it becomes more difficult to control it, which is a blessing.
Prior to T.V. children DID listen to the news on the radio, read newspapers, and saw, ON A BIG SCREEN, in movie theatres, at a time when everyone was going to the movies at least once a week, usually many more times, THE MOVIETONE NEWS newsreels! Sure, it wasn't like seeing something as it happened, but then, neither are many events, on T.V., as something happens!
Nam? That was not much of a big deal compared to seeing WW II footage on a huge movie screen, with ads afterward telling everyone to "BUY BONDS"!
And even before we were in WW II, there were films of Hitler, Nazis, Mussolini, etc. in the newsreels.
And no, I'm not old enough to have actually seen that all, in a movie theatre in the 1930s and early '40s; but as a young child, I did see such newsreels of the Korean War...AND I know history.
Very true. Two words: Mass Media. Television, newspapers, radio, magazines, music, etc. Underground media also. Counterculture media. Everybody everywhere was immediately made aware of anything anywhere. The left and right coasts now had current awareness of each other. England and the States picked up on each other’s changing cultures. London mimicked San Fran and L.A. There was a mass worldwide coming of age.