I was thinking the same. 1968 was one of the most turbulent years in US history. Tet offensive in Feb, LBJ pulls out of reelection in March, MLK assassination in April, RFK assassination in June, protests worldwide and at DNC convention in Chicago, athlete protest at Olympics, close election in November, exciting Apollo space missions during the year.
Not saying they have to go all topical in this show - it's really a show about one family in Alabama, but a little surprising. At least they did address Vietnam in this episode.