Those data points appear as circular flashes without a line, there are quite a few of them there. The app appeals to a lot of long distance Couples so the map is somewhat biased towards long distance communication.
Also if you look at big cities (LA, NYC, SF) you'll see a continuous stream of circles flashing without lines. So the data just overlaps a lot.
Also if you look at big cities (LA, NYC, SF) you'll see a continuous stream of circles flashing without lines. So the data just overlaps a lot.