In the county where I live, nearly 79% of voters registered as Democrats (and more registered as unaffiliated than Republican) for the 2016 election, and this was nearly 85% for the 2018 primary. However, county-level offices are partisan, which means that the Democratic primary effectively is the election, for the county government. If you aren’t registered as a Democrat (I was unaffiliated until 2016), a large portion of the primary ballot is blank (maybe a “yes/no” on a couple of bond issues etc.), and in the general election you basically get to rubber-stamp whoever made it onto the ballot as a Democrat.
I recall reading something similar here on the BBS, except it was about the Republican party being dominant in that place (somewhere in WV).
