Pretty astonishing to see how close together median Democrats and Republicans were in 1997.
From Sociological Images:
A recent Pew Report reported that in 1994, 64% of Republicans were more conservative than the median Democrat on a political values scale. By 2014, 92% of Republicans were more conservative than the median Democrat. Democrats have become more consistently liberal in their political values and Republicans have become more consistently conservative. And this has led to increasing political polarization.
You might think ideological commitments naturally come in groupings. But there are lots of illogical pairings without natural connections. Why, for instance, should how you feel about school vouchers be related to how you feel about global warming, whether police officers use excessive force against Black Americans, or whether displays of military strength are the best method of ensuring peace? The four issues are completely separate. But, if your Facebook feed looks anything like mine, knowing someone's opinion about any one of these issues gives you enough information to feel reasonably confident predicting their opinions about the other three. That's what ideological consistency looks like.