The most common disruptions at precincts are late openings, lack of staffing and voting machine issues, according to Jeff Greenburg, a 13-year election director veteran. He is now a senior advisor on election administration for The Committee of Seventy, a nonpartisan organization focusing on engagement and public policy advocacy.

As all eyes look to Pennsylvania, voters across the Commonwealth took to the polls to cast their ballots. With more than one million ballots already sent in by mail, millions more are expected to be cast.