Baltimore is a one-party city, so much so that it hasn't had a Republican mayor since 1967. Registered Democrats vastly outnumber any other party registration, having a tenfold advantage over the Republican Party. It's as blue as a city could get.
The consequence of this is November elections are inconsequential. The winner of the closed Democratic mayoral primary, for instance, might as well be sworn in the next day, and he or she can win with a marginal share of the total registered voting population. Voters outside the Democratic Party have no voice in the process.