The north-eastern US state of Pennsylvania is at the heart of the "Rust Belt". Its economy was historically built around mining, but has suffered greatly from industrial decline since the 1970s. Blue collar workers decide the result here, which can be decisive in the race to the White House. Since 1992, Pennsylvania has voted for the Democratic candidate. But in 2016, Donald Trump narrowly won the Keystone State by wooing disillusioned voters. How will they vote this time? Our team reports from Joe Biden's home state, where the economy remains a key concern.