The Republicans always won Eastern Tennessee in presidential elections, even at the party's nadir in 1936. Does anyone know why this was the case?
More examples: 1944 and 1924. In fact, Johnson County in Tennessee had the highest percentage of votes for Coolidge among all the counties in the nation with an amazing 91% of the county voting for Coolidge in 1924.
Eastern Tennessee and Appalachian country in general was deeply hostile to secession and proudly Unionist during the Civil War. The poor, isolated mountainous white population had felt deep hostility towards the agrarian, slaveholding, plantation-minded leaders of the Democratic Party during and after the war. If you wanted to find a "scalawag" or Southern collaborator with the Union occupation during Reconstruction, western North Carolina and eastern Tennessee were good places to look.
Long story short, much of the South was super-Democratic for a century over the memory of the Civil War. Eastern Tennessee, the most pro-Union part of the South, was Republican...over the memory of the Civil War. Even as the GOP faded into nonexistence over most of the South 1875-1890 eastern Tennessee remained bedrock Republican and, pretty uniquely, has remained so to present.