There’s some good news for women living in New Mexico: On average, women there face one of the smallest differences in wages between the genders of any state in the country. But they still need to put away $1.18 for every $1 a man saves to accumulate an equivalent nest egg in retirement.

Women working in New Mexico earned about 85 cents for every $1 men made in 2015 — the seventh smallest wage gap in the U.S. New Mexico was also among the 10 states charting the most improvement in the wage gap from 2007 to 2015, the latest data available, according to a new studyby NerdWallet.

Nationwide, women, on average, earned 80 cents for every $1 men made in 2015, based on median income — that’s up from 77.5 cents in 2007, the analysis of U.S. Census Bureau data shows.

Each year, U.S. women must put aside savings at an average rate of $1.25 to every $1 a man invests in a 401(k), traditional individual retirement account,Roth IRA or other investment plan to save an equivalent amount, the study found.

While pay parity remains elusive, the gap is closing more in some states than in others, which translates into a smaller shortfall in retirement savings. For example, in New York, the state with the narrowest wage gap, women must invest an average of $1.13 for every $1 to catch up to men. In Oklahoma — the worst state for wage gap improvement during the same period — women would need to put away $1.37 for every $1 a man saves there.

Both men and women struggle to save for retirement. The National Retirement Risk Index suggests roughly half of American families aren’t saving enough to maintain their standard of living in retirement. But the wage gap can make the challenge more pronounced for women, who live, on average, five years longer than men.

What’s behind the wage gap? Research suggests the issue isn’t so much that a woman working any particular job makes less than her male colleague; rather, it’s that the odds are greater that he will rise to upper management and earn more.

As well, a 2014 Harvard study suggests women are far more likely to take career breaks for child and elder care, which ends up limiting the number of women working in more time-consuming jobs with little flexibility for family needs.

To help keep the wage gap from expanding into an even larger retirement shortfall, experts suggest these tips to maximize savings:

Here are the states where women’s incomes average the most — or fewest — cents on the dollar compared with men, and where the pay gap saw the most — or least — improvement. If your state isn’t on one of these lists, you can find it here.

10 states with the smallest wage gaps in 2015

10 states with the largest wage gaps in 2015

10 states where the wage gap improved the most, 2007-2015

10 states where the wage gap improved the least, 2007-2015

Kevin Voigt is a staff writer at NerdWallet, a personal finance website. Email: kevin@nerdwallet.com. Twitter: @kevinvoigt. Jonathan Todd is a data analyst at NerdWallet. Email: jonathan.todd@nerdwallet.com.

The article Women in New Mexico See Smaller Wage Gap but May Fall Short on Retirement originally appeared on NerdWallet.