Women workers in Illinois who belong to a labor union earn an average of $122 more per week than their non-unionized counterparts.

That's according to a recent analysis by the Institute for Women's Policy Research (IWPR) on the "union advantage for women" in terms of wages and benefits.

The group found that unionized women earn more than non-unionized women in every U.S. state and are more likely to have a pension plan and receive health insurance coverage through their job.

The gender wage gap is also smaller among unionized workers, the findings showed. Women represented by a union earn 88.7 cents for each dollar unionized men earn. That gap widens to 78.3 cents between all women and men.

"This research shows that it pays to be in a union, especially if you are a woman," said IWPR President Heidi Hartmann. "Not only do union women experience a much narrower gender wage gap with men than women overall, they also earn hundreds of dollars more per week than non-union women, with greater access to critical benefits that can ensure their longterm financial security and well-being."

Unionized women nationwide make $212 more per week, on average, than their non-unionized counterparts. Additional weekly earnings of unionized women are large enough to cover a week of full-time child care costs in 32 states, IWPR found.

Illinois was not among those 32 states.

While the union wage advantage for Illinois women is $122 per week, the average weekly cost of full-time child care at a daycare center is $242, according to the analysis.

Another takeaway from the report is that women represent a growing proportion of the union workforce. They currently make up 46 percent of union workers in the U.S. and nearly 44 percent in Illinois.

"Women's share of union members has increased in each of the last three decades, from 33.6 percent in 1984, to 39.7 in 1994, and 42.6 in 2004," the report says, "and women are projected to be the majority of union members by 2025."

Among all workers nationwide, nearly 12 percent of women and 13 percent of men are unionized. The female and male unionization rates in Illinois are 15 percent and 18 percent, respectively.

IWPR researchers also looked at the situation for women in the 25 states with "right-to-work" policies, which prohibit labor contracts requiring that workers pay union dues as a condition of employment.

Statewide right-to-work policies drive down wages for all workers, according to the report. In right-to-work states, overall wages are 4.4 percent lower for women and 1.7 percent lower for men.

The share of women who are unionized is generally higher in states without right-to-work measures, the report says.

"Union representation brings with it greater pay transparency and helps ensure that employers set pay based on objective criteria, such as skill, effort, and responsibility," added report co-author and IWPR Study Director Ariane Hegewisch. "Unfortunately, many women around the country are not able to experience this union advantage."