Editor's Note: (Marianne Schnall is the author of "What Will It Take to Make a Woman President? Conversations about Women, Leadership and Power" and the founder of Feminist.com and the "What Will It Take" movement. The opinions expressed in this commentary are solely those of the author. View more opinion on CNN.)
(CNN) Although Republican candidate Martha McSally lost the tight Arizona Senate race to Democrat Kyrsten Sinema in the midterms, McSally is still headed for the Senate. Arizona Gov. Doug Ducey announced on Tuesday that he is appointing McSally to finish out the term of the late Sen. John McCain, presenting a rare and significant opportunity to further advance women's political leadership in the state of Arizona and across the nation.
What's immediately notable is that not only has Arizona elected its first female to the Senate with Sinema, but now Arizona and its neighbor Nevada will join the ranks of a handful of other states that have two female senators representing them in the upper house of Congress. Only four other states -- California, Minnesota, New Hampshire and Washington -- can say the same.
California first achieved this milestone in 1992 when it elected Dianne Feinstein and Barbara Boxer. This followed the Clarence Thomas-Anita Hill hearings, which galvanized the nation around gender politics in what became known as the "Year of the Woman."
The resulting increase in women's representation in Congress that year (with a record six female senators and 24 women elected to the House) has been dramatically eclipsed by the historic wave of women who ran and won seats in the House and Senate in the 2018 midterm elections. Many argue this influx was fueled by outrage that began with the election of Donald Trump and reached its zenith when Supreme Court Justice Brett Kavanaugh was confirmed after Christine Blasey Ford testified against him on charges of sexual assault. (Kavanaugh vehemently denied all charges.)
Now Sinema and McSally, who notably resolved their tight race without rancor, have the opportunity to show the nation the difference increased women's political leadership can make.
The phenomenon of women elected to top positions in clusters was the subject of a 2014 study commissioned by Political Parity, a project of Swanee Hunt Alternatives. The study explored the "multiplier effect" of women elected to a state's three top offices (the US Senate and/or the governorship) over a relatively short period to determine if there are measurable factors driving their success in particular states.
Now, in this new Year of the Woman, Arizona will join an expanding list of states that have had women in two or more of a state's three top jobs since 1992: Alaska, California, Hawaii, Kansas, Louisiana, Maine, Michigan, Minnesota, New Hampshire, New York, North Carolina, Texas and Washington.
According to the study, the rise of women to these positions is most likely to happen in states that are larger, comprised of better-educated and diverse populations, and where Democrats dominate. California, notable for having two female senators (Dianne Feinstein, and then Kamala Harris succeeding Barbara Boxer) since 1992, is the clearest example.
However, Arizona, by no means dominated by Democrats, is a fascinating outlier, though the state fits the study's "broken-barrier" correlation. Political insiders watched as Democrat Rose Mofford became their first female governor in 1988. Once Mofford had broken that barrier, Republican Jane Dee Hull became governor in 1997.
Indeed, Arizona's history is replete with strong women who have long made strides in the state legislature. The state leads the nation in electing women as governor -- two Democrats and two Republicans -- and ties with Vermont for the highest proportion of women in legislatures at 40%.
In short, women around the nation, elected in record numbers, have accelerated the pace of change. At the time the Political Parity study was conducted, many complained that it would be more than a century before women achieved parity in the US Congress. This year's midterm election may have moved up the horizon.
Arizona is yet another example of the seismic shift underway in women's representation across government. The 2019 freshman class of women in Congress will be the largest ever for a total of 102 female representatives and 25 female senators -- increasing female representation in Congress from 20% to 23.7%. These gains were amplified by the historic increase in women voting, marching, becoming civically engaged and making their voice heard.
Why does it matter? Political science research indicates that when women achieve a critical mass (20-30%) in a government body, not only does the culture of that body shift away from the "smoke-filled room" to more transparent, family-friendly processes,but it also produces better results with an emphasis on policies that invest in areas like health and education. Simply put, more women in power means better governance for all of us.
The promising increase in women's political participation is a significant step toward leading us to parity in politics as well as other sectors of society. But complacency can be dangerous; we must continue to actively push for women's political progress because even with the recent gains in the midterm elections, women are still far from having equal representation.
Mentorship is one way to keep the number of female politicians on the rise. In states like Arizona, with two or more women in the three top jobs, those women and other political leaders can accelerate the multiplier effect. Top elected women can groom future leaders (much like Hillary Clinton did with New York Sen. Kirsten Gillibrand), and they can actively participate in networking to elevate women into the pipeline for state and national office.
We can also be proactive in encouraging women to run (or consider running ourselves) in races for local lower-level offices. According to the Political Parity research, almost half of all members of Congress served previously in their state legislatures, so encouraging more women to run for these offices correlates significantly with a state electing women as senators and/or governors.
In general, we can also support diverse candidates by donating to their campaigns, volunteering and voting. We can speak out to protect against voter disenfranchisement, speak out against sexist media treatment of female leaders, as well as support female candidates when they are in office.
The shift to women's political leadership is still a long way from complete. But Arizona joining the few other states that have two female senators has just moved us further down the road toward a more reflective and equal democracy that represents us all.
Correction: This piece originally stated Janet Napolitano was the first female governor of Arizona. She was the third.