Voided ballots are verified at the Boulder County Clerk and Recorder's office on Monday, Oct. 15, 2018.

(Nathaniel Minor/CPR News)

Security experts say Colorado is one of the most reliable places to cast a ballot. That’s largely because of an old technology: good, old-fashioned wood pulp.

Almost every Coloradan will cast a ballot with a pen and paper this fall. If hackers do break into the system, paper ballots become the ultimate failsafe.

This is the story of how Colorado built one of the safest election systems in the country --and why defending against hackers is only half the battle. The other half is convincing voters their ballot will actually count.