The state's secretary of state told CNN she felt it was a necessary step to ensure Colorado maintains its position as a national leader on election security.

The decision is a further step toward prioritizing the role of human eye, rather than computers to count votes.

In recent years — after researchers have repeatedly demonstrated it's possible to hack many voting machines in particular circumstances and the US intelligence community detailed Russia's interference in the 2016 election — both government and industry leaders have reached a general consensus that the US needs to use paper ballots so that elections can be properly audited.

But some states have purchased voting machines that print out a paper receipt with either a QR (short for "quick response") or a more traditional barcode — something a computer can read, but a human cannot — which can then be easily scanned and tallied to represent a voter's choices.

But those codes are still controversial and experts warn that even though they're on paper, elections still need to be audited before results are certified.