Removing the city limits/expansion zones dotted white lines?

I swear that up until about 10 minutes ago I didn't see the dotted white line around the edge of my city and all my expansion zones available unless I clicked on an expansion zone, it was otherwise invisible, but now the dotted white line is constantly around the edge of my city and all the available expansion zones and I find it annoying. Am I right and it was normally invisible unless you clicked an expansion zone or has it always been there and now I'm focusing on it? How do I make it invisible again during normal gameplay? I tried restarting the app and no luck.