Blame the early ballots that get dropped off on Election Day at the polls. Stir in increasingly competitive contests, and it adds up to days' worth of waiting for a definitive result. Maricopa County estimated vote counting would run 10-13 days before every ballot is counted.

The more last-minute early ballots are received, the longer it may take to count votes and determine tight races.

The results in Arizona are expected to be finalized later than most states because Arizona allows voters to turn in mail-in ballots on Election Day at their polling place. Those mail-in ballots must be cured, verified and signatures must be checked before they can be tallied.