First lady Michelle Obama was visiting China with her daughters and mother in 2014 when she remarked to her Chinese counterpart, Peng Liyuan, that it was “very rare” for her to travel abroad.

The sentiment quickly drew scorn from conservative pundits in the United States who mused about her expensive overseas trips to Africa, Europe and India.

But after nearly eight years, the first lady has been proven correct, at least by comparison to the two women who preceded her, Laura Bush and Hillary Clinton. Although official statistics are hard to come by, figures compiled by the National Taxpayers Union show that Obama has traveled abroad less than half as often as Bush and Clinton.

Obama has made 22 foreign trips and spent 116 days outside the country, according to the NTU analysis, compared to 46 trips and 212 days for Bush and 47 trips and 274 days for Clinton.

Clockwise from bottom left, first lady Michelle Obama; her mother, Marian Robinson; and daughters Malia and Sasha arrive in Beijing on March 20, 2014. (Wang Ye/Xinhua via Reuters)

East Wing aides and outside analysts suggested several reasons to explain the contrast, foremost among them the fact that she and the president have raised their two young daughters in the White House.

“Mrs. Obama said she didn’t need to race away from home,” said Anita McBride, Bush’s former chief of staff who now runs a program on first ladies at American University. “She was very protective of her schedule from day one.”

Yet Obama also took a different approach to her policy work than did her predecessors, focusing more heavily on a domestic agenda. Her chief initiative, Let’s Move!, was an effort to combat childhood obesity, and she also worked closely on the Joining Forces program to help military families.

The first lady’s office is part of the Executive Office of the President, with a staff and travel budget funded by taxpayers, but the official role of the president’s spouse is not formally defined. Since 1901, when Ida McKinley popped across the U.S. border into Juarez, Mexico, to attend a brunch at a private residence, first ladies have taken trips to other countries — for personal reasons but also as extensions of their husbands’ diplomatic outreach.

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Until Clinton, Eleanor Roosevelt was the most well-traveled first lady, visiting Europe and the South Pacific during World War II as a representative of the American Red Cross.

Clinton, who also raised a young daughter in the White House, revved up the engines of her Air Force jet for 141 stops around the globe, an itinerary that began in earnest during President Bill Clinton’s second year in office.

After a failed effort to help lead a health-care reform bill through Congress in the first year, Hillary Clinton turned her focus abroad. One of her first stops was a United Nations conference on social development in Copenhagen, where Clinton substituted for Vice President Al Gore.

“She was the superstar of the conference,” recalled Lissa Muscatine, a former journalist who became Clinton’s speechwriter and adviser. At the United Nations World Conference on Women in Beijing in 1995, her declaration that “women’s rights are human rights” made headlines around the world.

“She realized she could have an impact,” Muscatine said, “and use the world stage to not only speak out on behalf of women’s rights and human rights but galvanizing people to act on those things.”

Hillary Clinton meets U.S. soldiers at Camp Alicia in northern Bosnia on March 25, 1996. (Win McNamee/Reuters)

Laura Bush entered the White House when her twin daughters were in college. Unlike Clinton, she was not intimately involved in her husband’s domestic governing agenda. But she took on an active role in foreign affairs in the wake of the Sept. 11, 2001, terrorist attacks that scrambled the Bush administration’s engagement abroad.

Bush traveled to Afghanistan three times to help promote education initiatives for girls after the U.S.-backed overthrow of the Taliban. She also took a personal interest in promoting social programs in Burma, then run by a repressive military junta.

And she was a frequent companion with President George W. Bush to international summits, something Michelle Obama has shied away from.

“Her view was that it was valuable and important for the American first lady to be there,” McBride said.

Laura Bush pays respect to Jews and other World War II prisoners who suffered at the Nazi concentration camp in Terezin, near Prague in the Czech Republic in 2002. (J. Scott Applewhite/Associated Press)

By contrast, Michelle Obama did not launch a foreign policy initiative until early 2015, when she announced the Let Girls Learn program. Since then, she has made seven trips abroad, many supporting the initiative; it has been her most sustained stretch of international travel since she took five trips overseas during President Obama’s first year in office.

The Obamas entered the White House during a global recession and at a time when Barack Obama had campaigned on ending the long U.S. military conflicts in Afghanistan and Iraq. So it made sense that the first lady focused more heavily on domestic issues, said MaryAnne Borrelli, a professor of government at Connecticut College who has studied the role of first ladies.

Her focus “is not to be understood as dismissing international affairs,” Borrelli said.

First ladies have at times blurred the line between personal and official visits. On several occasions, Obama has brought along her daughters, Malia and Sasha, and her mother, Marian Robinson, who lives in the White House.

But she learned early on that the scrutiny of her travel would be intensive. In 2010, she was criticized by government watchdog groups over the cost of a vacation to a Mediterranean beach in Spain with her mother, children and two friends. A New York tabloid labeled her a “modern-day Marie Antoinette.”

Before leaving, Obama made a visit to the king and queen of Spain, transforming the trip into more of a diplomatic visit.

“She never made that mistake again,” McBride said. “It was just not worth it.”