Mail-in ballots and security measures contribute to counting delays in California's close contests, an election expert says, and last-minute voters in the governor's race may slow things down further.

California's governor's race is tightening as many Democratic voters appear to be waiting until the final hours to cast their ballots.

With a glut of mail-in ballots and cushy timeline for counties to process them, learning who wins California races can be quite the waiting game.