Ms. Palin, who likes to call female candidates "mama grizzlies," opened her message by saying she and her family were headed to Kodiak Island to meet with logging families.
"As we work and sightsee on America's largest island, we'll get to view more majestic bears, so now is a good time to draw attention to the political equivalent of the species," she wrote.
Kodiak Island is 3,588 square miles, according to the Alaska Office of Economic Development. The island of Hawaii is 4,028 square miles, according to Hawaii's Department of Business, Economic Development and Tourism.
Palin, who briefly attended college in Hawaii and vacationed there last year, also overlooked some key facts in saying Ayotte "battled all the way to the U.S. Supreme Court to protect the rights of New Hampshire parents — and won!"
Palin mentioned the case three times in seven paragraphs, concluding that Ayotte will fight for New Hampshire voters "just as passionately and fearlessly as she fought for you in the highest court of the land."
As New Hampshire attorney general in 2005, Ayotte defended a New Hampshire law requiring that a parent be notified 48 hours before a minor child had an abortion. Steering clear of a major ruling on abortion, the US Supreme Court sent the case back to the federal court that had declared it unconstitutional because it made no exception for a medical emergency that threatens a girl's health. The law was later repealed without having ever taken effect.
Ayotte's campaign touted her role in the case.
"New Hampshire's parental notification law had been completely invalidated before Kelly appealed the First Circuit's decision to the Supreme Court, which ruled unanimously to reverse the lower court's decision and remand it for further review," spokesman Jeff Grappone said in an e-mailed statement. "Just because the Democrat-controlled Legislature repealed the state statute before the lower court revisited the case doesn't mean it wasn't an important victory for states' rights to regulate abortion."
Ayotte, who left her job in 2009 to run for Senate, said she was honored to have the support of Palin, a former Alaska governor.
"Governor Palin is a conservative icon who has brought enormous energy to our party," she said. "As governor, she took on the entrenched special interests to deliver results."
Though many consider Ayotte the front-runner, she faces several strong opponents, including businessman Bill Binnie, whom Palin referred to as a "self-funded millionaire running with an R next to his name who likes Obamacare and cap-and-tax."
"I have consistently said I will win my campaign in Tilton, New Hampshire, not Washington, D.C.," said Mr. Binnie, who supports neither President Obama's health-care overhaul legislation nor a cap-and-trade system to curb carbon emissions.
Palin's Kodiak Island error wasn't her first geography goof connected to New Hampshire. When she visited the state as the Republican vice presidential nominee in 2008, she spoke about a New Hampshire city and "other parts of this great Northwest," even though it's in the Northeast.