Expense forms describe the girls' official purpose as "NGA Governor's Youth Programs and family activities." But those programs were activities designed to keep children busy, a service provided by the NGA to accommodate governors and their families, NGA spokeswoman Jodi Omear said.

In addition to the commercial flights, the children have traveled dozens of times with Palin on a state plane. For these flights, the total cost of operating the plane, at $971 an hour, was about $55,000, according to state flight logs. The cost of operating the state plane does not increase when the children join their mother.

The organizer of an American Heart Association luncheon on Feb. 15 in Fairbanks said Palin asked to bring daughter Piper to the event, and the organizer said she was surprised when Palin showed up with daughter Willow and Bristol as well.

The three Palin daughters shared a room separate from their mother at the Princess Lodge in Fairbanks for two nights, at a cost to the state of $129 per night.

The luncheon took place before Palin's husband, Todd, finished fourth in the 2,000-mile Iron Dog snowmobile race, also in Fairbanks. The family greeted him at the finish line.

When Palin showed up at the luncheon with not just Piper but also Willow and Bristol, organizers had to scramble to make room at the main table, said Janet Bartels, who set up the event.

"When it's the governor, you just make it happen," she said.

The state is already reviewing nearly $17,000 in per diem payments to Palin for more than 300 nights she slept at her own home, 40 miles from her satellite office in Anchorage.

Tony Knowles, a Democratic former governor of Alaska who lost to Palin in a 2006 bid to reclaim the job, said he never charged the state for his three children's commercial flights or claimed their travel as official state business.

Knowles, who was governor from 1994 to 2002, is the only other recent Alaska governor who had school-age children while in office.

"There was no valid reason for the children to be along on state business," said Knowles, a supporter of Democratic presidential nominee Barack Obama. "I cannot recall any instance during my eight years as governor where it would have been appropriate to claim they performed state business."

Knowles said he brought his children to one NGA event while in office but didn't charge the state for their trip.

In February 2007, the three girls flew from Juneau to Anchorage on Alaska Airlines. Palin charged the state for the $519.30 round-trip ticket for each girl, and noted on the expense form that the daughters accompanied her to "open the start of the Iron Dog race."

The children and their mother then watched as Todd Palin and other racers started the competition, which Todd won that year. Palin later had the relevant expense forms changed to describe the girls' business as "First Family official starter for the start of the Iron Dog race."

The Palins began charging the state for commercial flights after the governor kept a 2006 campaign promise to sell a jet bought by her predecessor.

Palin put the jet up for sale on eBay, a move she later trumpeted in her star-making speech at the Republican National Convention, and it was ultimately sold by the state at a loss.

That left only one high-performance aircraft deemed safe enough for her to use — a 1980 twin-engine King Air assigned to the public safety agency but, according to flight logs, out of service for maintenance and repairs about a third of the time Palin has been governor.