For the poll watchers and sundry political junkies out there, here are some maps of straight party ticket voting from the 2007 general election, which was the last time we voted for Allegheny County Executive(ACE). The main thing to keep in mind is that race was uncontested with no Republican on the ballot at all for ACE. Whether that pushed up or pushed down the straight ticket Democratic votes I am not sure. What happened to the straight party Republican votes when there was no Republican on the ballot for ACE is one of those existential questions.
Note the colors and legend are consistent across the two maps, but on the Republican side I don't think there is a single voting district with 25% or higher straight ticket voting. So the two darkest colors are not there anywhere. These are both percentages among ballots cast that cycle.