Will Pennsylvania be the Keystone to the 2020 Election?

Trump has seen a small improvement in the polls in the final week of the campaign.  He has slight leads of 1%-2% in the critical states of Iowa and Ohio.  He is within the margin of error, less than 3% in Florida, North Carolina, Georgia, and Arizona.  If Trump can manage to win all of those close states, as well as the states where he is expected to win more easily, he could have 259 electoral votes.  

Three states that Trump won in 2016 seem to be leaning to Biden: Wisconsin, Michigan, and Pennsylvania.  Biden's lead in Wisconsin has widened in polls to around 9%-10%.  Michigan gives a 5%-6% point Biden lead in the polls.  If Biden wins Michigan, both candidates could have 259 votes.  At that point, Pennsylvania, with its 20 electoral votes, would decide the election.  As of election day, polls show Biden with a 3%-4% lead in Pennsylvania, within the margin of error, and in a State where Trump has defeated poll expectations before.

Pennsylvania election law does not permit poll workers to begin counting paper ballots until election day.  So if the election comes down to Pennsylvania, what happens.

If you are old enough, you remember Florida in the 2000 elections, when that decisive state took weeks to turn in a final count.  Both parties attempted to manipulate the process, either through the courts, in the media, or in street protests.  That process could repeat itself in Pennsylvania in 2020, on steroids.

Given the level of emotions and accusations of cheating and unfair election practices, the whole legitimacy of representative elected government comes into question.

None of this may happen if a few other States put a candidate so far ahead that the outcome in Pennsylvania won't be determinative.  Of course it is also possible that two or three other states are too close to call and that we have both parties pushing their desired outcome in several key states.

The sad case is that if the election is close, it may become violent.  If it becomes violent, the State of the Union could be in question to such an extent for the first time since the 1860's.