Re: American Political Parties: The Switch?
Things change or transmutate, or whatever you want to call it. Political "parties" almost always coalesce around objections to some major issue. Jeffersonian democrats formed - almost without realizing it - due to distrust of central government and objections to Federalist policies.
In the mid 20th century, Southern Democrats had been descendants of Jeffersonian and Jacksonian democratic republicans. They felt left out in terms of their interests after the Civil Rights movement of the 50s and 60s. The Republican Party's "Southern Strategy" aimed to capitalize on that disaffection, and from about 1980 it was successful. That was all about winning elections.
In 1860, Democrats were essentially conservative politically; Republicans were seen as the radicals. Modern labels have changed.
However, people tend to their own self interests, so as modern Republicans morphed into a more conservative (or neo-conservative) grouping, conservative Southerners gravitated more toward that party. Of course, not everyone did, but the change has been noticeable in the last 30 years.
Going with a perceived flow is usually just good politics (often having little to do with public policy though).