Actually, take a look at the "red/blue" maps of the last election.
Take a look at the one that does a breakdown by county instead of state. You'll notice that the blue vote is concentrated in cities and the red vote in rural areas. You'll also note that a great many cities tend to be near harbors or navigable rivers; in the latter case, especially where two rivers meet or where there is a set of rapids, etc., that make that spot difficult to navigate. If water levels rose world wide, cities (on the coasts, most particularly) would be disproportionately affected.
Cities would also be impacted by a fall in sea level.
Boston just petitioned the Feds for permission to re-dredge its main shipping channel, which is 40 feet deep at high tide- the big boats have difficulty getting in and out. A ten foot drop in sea level would mean curtains for most coastal city's shipping, until they rebuilt docks and re-dreged. (It would be reported on the Dredge Report online no doubt).