When you ask a working Minnesota mom what she wants for Mother’s Day, don’t be surprised if she says, “A day off.”

In Minnesota, moms work harder than almost anywhere in the country. In 8 of 10 Minnesota families, they are sole, primary, or co-breadwinners. That’s the second-highest share of moms in the country who work outside the home.

Nationally, 73 percent of women who have children under age 18 at home are in the labor force, working full-time, part-time or actively looking for work.

Midwestern states lead the nation. South Dakota has the most working moms (84 percent), followed by Minnesota, Iowa and Nebraska (each with 81 percent), and then Wisconsin (80 percent), according to a Star Tribune analysis of census microdata from IPUMS-USA, University of Minnesota.

The lowest rate is in Utah, with 63 percent of moms working outside the home.

The Star Tribune also looked at microdata from the 1990 census to get a sense of whether more mothers are working now than in the past. The labor force participation rate back then for Minnesota moms was a little bit lower, but the state was still in the top five.

Minnesota’s labor force participation rate varies for moms, depending on circumstances and demographics.

For example, the rate is lower – 76 percent – for those who have a child under the age of one, and significantly lower – 58 percent – for those with five or more children. Rates are roughly the same regardless of marital status, although divorced moms are more likely to have full-time work.

Women of color have lower participation rates, although they are up significantly compared with 1990.

It appears “women in Minnesota like to work,” says Kristine West, an assistant professor of economics at St. Catherine University. “Even after controlling for things like race and education, Minnesota women do have higher labor force participation rates than women elsewhere.”

Why is the rate of working moms unusually high in Minnesota compared to other states?

“We’re not sure. There are a lot of possibilities,” said Katie Genadek, a research scientist at the University of Minnesota. “Maybe it’s cultural – Midwesterners are hard-working – or maybe it has to do with wage equality or perhaps less gender discrimination. It’s likely a multitude of things.”

While there is no one answer why a greater share of Minnesota moms are in the labor force, data analyzed by the Star Tribune, and interviews with local economists, researchers and family social science experts lay out possible reasons:

Minnesota has a highly educated population, and well-educated women are likely to have careers that are stimulating, satisfying and reflective of their interests and passions. After having children, educated women feel a strong pull to stay engaged in a career.

Minnesota companies make it easier for moms to work. “Since the 1990s or even before, many large Minnesota companies have been on the leading edge of addressing the needs and wishes of working mothers – offering flex-time, job-sharing, good parental leave, childcare benefits and other benefits and amenities to support parents in achieving a healthy work-family integration,” said Marti Erickson, owner and co-host of the Mom Enough website and podcast, and a retired professor in the University of Minnesota’s Child Psychology and Family Social Science programs.

About 30 percent of Minnesota’s working moms are in part-time jobs (less than 35 hours per week), which is similar to the national rate but a bit lower than in 1990, the Star Tribune’s analysis shows.

There may be more female-dominated industries in the state, such as health care and education, and Minnesota may offer higher salaries than other states, Genadek said.

Minnesota has better wage equality for women and a history of supporting women’s rights and accepting women in leadership positions. Women who work full time and year-round make 80 percent of their male counterparts in Minnesota, compared with 77 percent nationally.

“Those general cultural attitudes make it easier for women to find the job or career path that works best for them and their families,” Erickson said.

Mothers are generationally influenced by their own mothers. "There is research from sociologists suggesting that if your mother worked, you're more likely to work, too," Genadek said.

Minnesota has a thriving economy, boasting an unemployment rate of 3.7 percent, compared with 5.4 percent nationwide.

Of course, a discussion of working mothers isn’t complete without talking about out-of-home child care, particularly how much it costs.

Center-based child care for an infant, as a percentage of income for a typical Minnesotan family, is the highest in the nation, according to an analysis by Child Care Aware of America, chewing up about 15 percent of a typical married couple family’s income. Having either an infant or a preschooler in a child care center in Minnesota costs more than college tuition, their latest study says.

Does the high demand for child care here drive up the cost? Maybe. But it doesn’t hold true for other states with high rates of working moms. South Dakota, for example, has the highest rate of labor force participation but the lowest child care cost, as a percentage of income.

Data Drop is a weekly feature that uses data analysis and visualizations to explain, surprise, inform and entertain readers on topics relevant to Minnesotans. Do you have an idea you'd like us to explore? Contact MaryJo Webster