FACTBOX-U.S. counties using automated signature verification software

Merced: All approved signatures reviewed by staff. Napa: Has not used previously. Software only used on ballots returned before Election Day. Denver: Software approves 20% of signatures, and staff checks about 5% of approvals. Douglas: Software approves 40% of signatures, and staff checks one in every 50 approvals.

U.S. election officials trying to deliver speedy results with limited staff have increasingly turned to software that matches signatures on ballot envelopes to voter records. At least 29 counties across eight states use the artificial intelligence technology on mail-in ballots to ease the workload of staff enforcing voter signature rules.

Parascript, the maker of the software, declined to identify users but said they included 30 of the top 100 counties by registered voters. Here is a list of users Reuters identified and basic details on their use of the software, if known.

CALIFORNIA Butte

Humboldt: Envelopes with no signature and those with very probable mismatches sorted out for staff review. Los Angeles

Marin: Software approves 75% of signatures, and staff checks a sampling. Merced: All approved signatures reviewed by staff.

Napa: Has not used previously. San Diego: All approved signatures reviewed by staff.

COLORADO Adams: Software approves 35% of signatures, and staff checks one in every 50 approvals.

Arapahoe: Software approves 50% of signatures, and staff checks at least one in every 37 approvals. Software only used on ballots returned before Election Day. Denver: Software approves 20% of signatures, and staff checks about 5% of approvals.

Douglas: Software approves 40% of signatures, and staff checks one in every 50 approvals. El Paso: Staff checks one in every 50 approvals.

Larimer: Software approves 50% of signatures, and staff checks one in every 50 approvals. FLORIDA

Broward Manatee: Software approves 30% of signatures.

Osceola: Software approves 50% to 60% of signatures. Seminole: Software approves 30% to 40% of signatures.

HAWAII Hawaii: Software approves 50% of signatures, and staff checks 5% of approvals.

Honolulu: Software approves 50% of signatures, and staff checks 1% of approvals. OREGON

Clackamas: Has not used previously. Lane

Marion: Software approves 60% of signatures. Multnomah: Software approves 55% of signatures, and staff checks 100% of first approvals and then a few in subsequent batches.

Washington: Software approves 60% of signatures, and staff checks 100% of first approvals and then a few in subsequent batches. NEVADA

Clark UTAH

Salt Lake: Software approves 50% of signatures, and staff checks 1% of approvals. Utah: Software approves 25% to 30% of signatures, and staff checks 1% of approvals.

Weber: Software approves 40% to 45% of signatures, and staff checks 1% of approvals. WASHINGTON

Pierce: Software approves 50% to 60% of signatures, and staff checks 5% plus the 10 least confident of the first approvals, then 3% plus 10 least confident in subsequent batches.