the article is playing fast and loose with the generational boundaries. They use the term Generation Jones for the later part of the Baby Boom plus a little beyond, 1954-1965.
The name comes from the phrase “keeping up with the Joneses”
Too much can be made of Presidential trends, take this for example:
Take the Missouri Compromise line (the southern border of Missouri) and extend it across the country.
From 1852, a few years before the Civil War, until 1960, every single elected President regardless of party came from above the line. That is 28 straight elections.
Then from 1964 to 2004, every single elected President regardless of party came from below the line. That’s 11 straight elections