Want To Make America Great Again? Support Working Women.

If Donald Trump, Jeb Bush and their fellow Republican presidential candidates truly want to make the United States “great again ," there’s actually a reasonably simple way to do it: support working women.

The U.S. once had the world's highest percentage of women in the workforce, but over the past quarter-century, we’ve fallen behind. Policies that make it easier for women to work could vault us to the top again -- and stimulate economic growth, too.   

If American women were to enter the job market at the same rate as men, work the same hours as men and take jobs in sectors with higher productivity (think more women in tech, fewer at Walmart), gross domestic product would grow 4.2 percent over the next 10 years, according to a report released last week from researchers at McKinsey & Company . (A report from the International Monetary Fund estimates even higher growth , 5 percent, if women participated equally in the workforce.) That’s about $4.3 trillion more than what our GDP growth would be if it chugs along at an expected rate of 2.6 percent, the researchers said.

“This is one of the biggest levers they could pull, and one of the easiest ways to get a significant jump in GDP growth,” Kweilin Ellingrud, a managing partner at McKinsey who worked on the report, told The Huffington Post.

The full report considered how greater gender equality would affect GDP -- a measure of all the economic activity in the country -- globally and by region. The researchers broke out the U.S. numbers for HuffPost.

The last time the U.S. economy approached 4.2 percent GDP growth was during the Clinton administration -- when GDP grew at 3.8 percent . It’s about the same growth rate Bush  is promising, and a bit less than what Trump said he’d deliver if elected president.

Bush and Trump both seem to believe they’ll increase GDP growth by cutting taxes on the rich, but economists have widely  debunked the idea that such a proposal would actually be effective.

The stampede of women into the workforce that began in the late 1960s was one of the key drivers  of U.S. economic growth in the second half of the 20th century, along with the invention of the Internet . 

But in recent decades, American women's ascendance in the workplace has flatlined. Since 1990, the percentage of U.S. women of working age (15-64) in the labor market has ticked up only one percentage point, to 75 percent. Meanwhile, European countries have surged ahead of us, according to data from the Organisation for Economic Co-operation and Development published in the Economic Report of the President .

Those countries were able to push the needle by enacting policies that support dual-income families: paid parental and sick leave, free universal preschool, subsidized child care and more pressure on businesses to enact policies that support parents. The U.S. doesn’t do any of that.

No Republican presidential candidate has voiced support for federally mandated paid parental leave  of the sort you see in all other major industrialized countries -- and they don't even talk about that other stuff. Democratic presidential candidate Hillary Clinton does support a modest amount of paid leave and free preschool  -- but she's hardly proposing the kinds of policies you'd find overseas, which are considered pretty far off the mainstream in the U.S.

Nearly one-third of the gap between the U.S. and these other countries can be traced back to the lack of work-family policies in the United States, according to a widely cited  study from two researchers at Cornell University .

The McKinsey report comes to a similar conclusion. The researchers outline four things that keep women out of the workforce around the world:

1. A lack of education
2. Restrictions on women’s financial and digital freedom
3. An absence of legal protections against discrimination and abuse
4. Time spent on “free labor,” uncompensated work at home and child care.  

The good news is that the U.S. is pretty great at addressing those first three problems -- well ahead of much of the developing world. It’s on the “free labor” front that we fall down. Women are still doing the bulk of housework and child care, even though about 70 percent of women  with children under the age of 18 have jobs. 

Are we, as a society, supporting these women so they can make the money that helps them care for their families? Are we making it relatively simple for a woman to have children and a career? We are not.

Many women, without access to paid parental leave, are back on the job just two weeks  after giving birth. Others choose lower-paying, part-time work and juggle an intense and exhausting  schedule of child care to scrape by. Some women who want to work must instead rely on government assistance because they cannot afford child care. Their lives, and the lives of their children, are measurably worse as a result.

Even at the highest levels  of the workforce, women -- and, increasingly, men -- are finding it too difficult to manage home and work duties, as Anne-Marie Slaughter argues in her new book, Unfinished Business.

The McKinsey researchers are not suggesting that women simply abandon home and enter the workforce, but that there are all kinds of ways to help men and women better balance the time they spend on unpaid and paid work, Mekala Krishnan, another researcher, told HuffPost in an email. They include better on-site child care facilities at businesses, flexible work policies and a more equitable distribution  of work between men and women.

Still, there’s a conservative argument that goes something like this: Well, if women work, then no one will have the babies!

In turns out the opposite is true. Indeed, in countries where it’s too hard to juggle motherhood and work, women choose work. Aiming to increase Japan's low birthrate and boost its economic growth, Prime Minister Shinzo Abe  recently announced the country would make preschool free of charge and give more support to mothers and fathers. 

“Work-family policies are always framed as some nice thing to do,” Avivah Wittenberg-Cox, CEO of a gender balance consulting firm that works with Fortune 100 companies, told HuffPost. But it’s so much more than that. This is an economic issue that affects everyone.