Nixon '72 in the South

[Adlai Stevenson]

Why in 1972 did Richard Nixon run so spectacularly well in the South?  He won almost 80% of the vote in Mississippi and in some counties must have come close to Democrat segregationist totals before the 1960s.  To do this he must have won some black voters, how did he manage that?  Or was McGovern so appallingly unpopular then?