The key counties to track on US election night

There are many counties that voted Democrat in the past but switched to Republican in 2016. 

Supporters of US president Donald Trump listen as he speaks during a campaign rally at Orlando Sanford International Airport. File picture: Evan Vucci

Faced with what may be a protracted vote count to determine the next US president, election watchers will be closely monitoring results in certain counties to get an early indication of where the vote is headed.

The list includes the most pivotal counties in the most pivotal states, as well as districts that could shed light on certain demographics or national trends.