I created and uploaded a video to YouTube. The description under the video, reproduced below, describes the methodology used:
https://www.youtube.com/watch?v=SsOlhNWbe1UStates are colored by the margin of victory (Democratic minus Republican voting percentage) for each state, after correcting for the US margin of victory for that election year. For example, in 2012, Pennsylvania had a value of +1.52%, meaning Pennsylvania's margin was 1.52% more Democratic than the national margin. The colors range from lighter (smaller margin) to darker (larger margin) for both Republicans (red) and Democrats (blue), and correspond to bands ranging from 0%-5%, 5%-10%, 10%-15%, 15%-20%, 20%-30%, and greater than 30%, respectively.
Data are from Dave Leip's Atlas (
https://uselectionatlas.org/). Maps made at mapchart (
http://mapchart.net/usa.html).