He correctly states that Democrats supported slavery and opposed civil rights for minorities as well as women’s suffrage, etc., while Republicans took the opposite view.
What Kokkonen fails to mention is the changing character of the two parties in years between presidents Abraham Lincoln and Richard Nixon.
During the 100 years following the Civil War, Northern Republicans were seen as progressive, while Western Republicans were aligned with Southern conservative Democrats.
This was true until President Lyndon Johnson signed the landmark civil rights legislation of the 1960s, and then asserted that he had just given the South to the Republicans for a generation.
Nixon then adopted his “Southern strategy” so the South became the bastion of conservative Republicans, instead of conservative Democrats, as the writer likely knows.
Kokkonen would have been more helpful to his readers’ historical knowledge if he had substituted “conservatives” for “Democrats” and “progressives” for “Republicans.” But, that was not his intent.