… One of our favorite metrics gauges partisanship in a state’s presidential voting by comparing it to the national vote margin. … If we take the average margin by which each state voted more Republican or more Democratic over the last 100 years, we get the chart below. …
There’s something interesting here. Since the 1990s, the margin by which states have been more Republican has indeed grown, while the margin by which states vote more Democratic has been relatively flat. This reinforces the idea that partisan loyalty has strengthened — but only on one side of the split. CONT.
Philip Bump, Washington Post