I was thinking about negative bellwethers, which are things that generally pick the losing candidate. A positive popular vote bellwether could be New Mexico dating back to 1964. This means it always picked the candidate winning the national popular vote for president. I was thinking about the opposite: a negative bellwether county. This is the best example of a negative popular vote bellwether I could find: Vermont gubernatorial elections relative to presidential elections in presidential years and House relative to the election 2 years after (midterm):
Year, VT voting for winning party nationally 2006, No 2008, No 2010, No 2012, Yes 2014, No 2016, No 2018, No 2020, No
I put 2020 in because I feel this is pretty safe. (Don't correct me for this.) At the county level (for president), what is the longest negative bellwether streak? Such a county, from 2000 on, would vote Bush, Kerry, McCain, Romney, and Trump. What county has done this?