It's just as much of an issue within the party itself in terms of a representation issue.
Below, each county in blue is the largest single county in terms of Democratic primary votes for that state. For each state below, the gray counties in said state produced as many votes in the 2016 Democratic presidential primary as the blue county in the state; the dark blue counties are a majority of the state's Democratic voting bloc (NV, UT, HI, IL, AZ). The general goal was to start with the counties that were least-populated/fewest number of Democratic primary voters in order to maximize the geographic visual effect.
Approximately 25% of the national Democratic primary/caucus vote (at the time this map was made; other states have voted since) came from the counties in blue. Another 25% came from the areas in gray, and the remaining 50% are in the counties in white (again, states where all counties are white are not included in that assessment).
What this shows in some states (chart below) - although it wasn't the original intent - is the huge extent to which suburban Democrats are a huge portion of the bloc. Take Texas, for instance: 70% of Democratic primary voters in the state were in the counties in white. For Georgia, it's 70% as well. In some of these states (more so Texas than Georgia), picking "the county with the most Democratic votes" really ends up being in vein, since there may be multiple urban counties with comparable numbers of Democratic votes - as well as many highly-populated suburban counties.
Missouri and Virginia were other ones that short of shocked me (50% being in the white counties for MO; 65% for VA).
Image ain't workin'
