On Feb. 13, 1968, Bobby Kennedy was a month from declaring for president and four months from an assassin's bullet. For two days in eastern Kentucky, he met people who were as poor and isolated as he was rich and famous. Somehow, they clicked. Now 50 years later, what was Kennedy country is Trump country. Children of Kennedy Democrats are Trump Republicans. And for those inspired by RFK in 1968, what should be a happy anniversary is instead an occasion to puzzle a drastic reversal of political fortune.