Election 2016: The race for battleground states

Teams for both Clinton and Trump are campaigning in Pennsylvania this week, and both campaigns' planes were parked on the same runway in Ohio recently. In a country of 50 states, why do some seem to get more attention come election time?

Katty Kay explains why the race to win battleground states is key to winning the 2016 election.

Edited by Franz Strasser. Produced by Mat Morrison.