Invisible LinesOur world has innumerable boundaries, ranging from the obviouslike an oceanto subtle differences in language or climate. Most of us cross invisible lines all the time, but don't stop to consider them. In Invisible Lines, geographer Maxim Samson presents 30 such unseen boundaries, intriguing and unexpected examples of the myriad ways in which we collectively engage with and experience the world. From football hooligans in Buenos Aires to air quality in