Some 50 years ago, the gunshot that changed American politics – indeed, changed America – was fired. Dallas, November 22, 1963. President John F. Kennedy – urged by Vice President Lyndon Johnson – made a long-planned trip to Texas. With the ’64 election just around the corner – and Texas support in question – the trip mattered. Kennedy went to Dallas. We know what happened next. But what if – by twist of fate – that day played out differently? What if the rain hadn’t stopped and a plastic bubble top would have covered the President’s car? What if he were not fatally injured? What if he lived? If you wonder about ANY of those questions, you’re not the only one: Jeff Greenfield, veteran and thoughtful analyst of politics, culture and media is also author of the fascinating new book, “If Kennedy Lived: The First and Second Terms of President John F. Kennedy: An Alternate History.”