I think traditional “bellwethers” have become meaningless due to the rapid demographic change happening in the US; not the one portrayed on the news (which is designed to prevent Americans from panicking), but the very real one happening in front of our eyes in maternity wards, schoolyards, and immigration offices. America is rapidly becoming much more Asian and Hispanic, and there is simply now way to use past models to project the behavior of those populations.
There are over 3,000 counties/parishes in the US. It is my guess that so called bellweathers are nothing more than a statistical outlier.