Joe Biden is leading Donald Trump in the national polls for the presidential election.
But that doesn’t guarantee the Democratic candidate victory. Hillary Clinton also had a clear lead over Trump in the polls for almost the entire 2016 campaign. She ended up losing in the electoral college.
Because the presidential voting system assigns each state a number of electoral college votes, which go to the state’s victor regardless of the margin of victory, a handful of swing states will probably decide the election and be targeted heavily by campaigners.
Each day, the Guardian’s poll tracker takes a rolling 14-day average of the polls in eight swing states.
In order to track how the race is developing in the areas that could decide the election, six of the eight states we focused on were those that flipped to Trump in 2016 after backing Barack Obama in 2012. Arizona and North Carolina were also added due to what they might tell us about a shifting electoral landscape – they could emerge as vital new swing states this year.