In 1991 there were only two female members of the United States Senate.

Then came the debacle of the hearings on Clarence Thomas' nomination to the Supreme Court - with their enduring images of an all-male Senate Judiciary Committee grilling Anita Hill on her allegations of Thomas' sexual harassment. It was an eye-opening moment for women nationwide.

The next year, more women ran, and five women became senators.

Fast-forward two decades. Voters on Nov. 6 ensured that 20 female senators would hold office in January, enough so that, for the first time, women will make up one-fifth of the seats in that powerful house of Congress.

It isn't close to parity - women make a little over half of the population. But it is a welcome step forward.

This year, like 1991, male public officials with foot-in-mouth disease gallantly did their part to help galvanize female voters.

Republicans who promised to focus on the economy instead took aim at limiting abortion rights even in cases of rape and incest. Several Republican candidates articulated truly antediluvian views on rape that appeared to rationalize and even minimize what is an all-too-common and horrifying event for women.

The result? Sen. Claire McCaskell, D- Mo., won a race she was once expected to lose, trouncing her opponent, Rep. Todd Akin, who said women acquire magical powers to prevent pregnancy during "legitimate rape."

Women overwhelmingly voted against Indiana Republican Richard E. Mourdock, who said during his Senate race that if women became pregnant as a result of rape, it was just "something that God intended to happen."

Nationwide, more women than men voted this year. Females made up 54 percent of those casting ballots. Women voters made the difference in several races that were once too close to call.

Elizabeth Warren's victory in Massachusetts was one; the race of Heidi Heitkamp of North Dakota, who won by only 3,000 votes, was another. Neither state had previously elected a woman to the U.S. Senate.

The same was true of Wisconsin, which elected Tammy Baldwin, the first openly gay senator, and Hawaii, which elected the first Asian woman to join the Senate. Progress, of course, is never a given - only change.

So will additional numbers of women make a difference? Absolutely.

One reason why is because the women of the Senate have established a bipartisan tradition of reaching across the aisle.

For many years, female senators have gathered for dinner every two months to concentrate on issues they can support together, and in so doing, have forged alliances and friendships.

They acknowledge their differences, but haven't allowed them to become barriers to collaboration. The women have worked on policies on shared issues of concern: health care, crime, reproductive rights, and family issues.

In a polarized political atmosphere in which too many in Congress have acted more like middle-schoolers fighting on the playground, the women in the Senate have shown how to get it done.

Too bad there will only be 20.