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There have been a number of important women trailblazers in American politics, but it has taken until now — the nation's 58th presidential election — for a new major milestone to be reached.

This week, Hillary Clinton will become the first woman to be the nominee of a major political party. And it will happen in the city where our system of government was formed nearly 230 years ago.

For Clinton, the moment carries another poignant bit of historical significance: Her mother, Dorothy Howell Rodham, was born on June 4, 1919 — the very day Congress passed the 19th amendment giving women the right to vote.

Clinton’s achievement comes at a time when political gender parity is closer than ever but the disparity remains stark.

For example, the U.S. ranks 94th in the world in the percentage of woman in the federal legislature, according to the Center for American Women in Politics, or CAWP. Just 20 percent of those serving in the U.S. House of Representatives and Senate are women.

For those who work to elect women to political office, Clinton’s achievement took far too long.

Hillary Clinton Alexander Tamargo / WireImage

“It’s taken a very long time,” said Susan Carroll, senior scholar at the CAWP. “I’ve been doing work on women in politics since the mid-1970s and I never thought it would take this long.”

Eleanor Smeal, the head of Feminist Majority and who has dedicated her long professional career to increasing women’s influence in politics, agrees.

“The only thing that surprises is how long it’s taken,” she said.

Jeanette Rankin of Wyoming became the first woman elected to Congress in 1917 but it took decades for women to see any real electoral success.

Experts on women in politics agree that it was the feminist movement of the 1970s that propelled women into the modern political sphere.

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“There’s a direct lineage between Hillary Clinton running now and the efforts of the activists in the ‘70s,” Carroll said.

1972 was a critical year for women in politics. Shirley Chisholm was not only the first African American woman to run for president, she was on the primary ballot in 12 states and had her name placed into nomination at the Democratic convention.

That same year was when both the House and the Senate passed the controversial Equal Rights Amendment, which sought to guarantee equal treatment of all regardless of gender. While it failed to ever gain the support of enough states for ratification, Eleanor Smeal, who was a leader in that fight, said the ERA campaign was tremendously successful.

“It kicked off the early movement,” Smeal said. “Tens of thousands of women were involved.”

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After the defeat of ERA, the very first organization was formed to help elect women into office. Called the Women’s Campaign Fund, it is a bipartisan group that promotes and provides resources to women running for office.

WCF led the way for the creation of Emily’s List, which is the most successful organization propelling women into the political sphere.

In 1976, just 18 women served in the 535-member House and Senate, but the next 16 years saw major progress.

Geraldine Ferraro became the first woman on a major party presidential ticket when Walter Mondale chose her his running mate in 1984.

“The fact the ticket was defeated temporarily set things back a little bit, but in the long run it really helped to pave the way for the women who have come after,” Carroll said.

And then the number of women in Congress nearly tripled. The 1992 election is known as the “year of the woman” because a record number of women were elected to the House and the Senate. Woman elected that year include Senators Barbara Boxer and Diane Feinstein, both of California, Patty Murray of Washington and Carol Moseley Braun of Illinois.

The year of women, which saw 52 women serving in Congress, was not only the result of the women’s rights movement, but also because women around the country saw how women were being treated by men in power.

Women candidates reacted to the events like how Anita Hill was questioned by an all-male Senate Judiciary Committee during Clarence Thomas’ nomination hearings to be Supreme Court justice. Murray, who was a pre-school teacher before her entrance into politics that year, has said that the Hill testimony compelled her to run.

And during the 1990’s, Clinton played a pivotal role for women in politics. She changed what it means to be First Lady by taking on a more policy-focused agenda.

The number of women continued elected to federal and local office continued to rise, although women winning elections is far more prevalent in the Democratic Party than the Republican Party, so has the number of women voters.

Women were a minority of voters until 1984 when Ferraro was on the ticket. During that election, women participation skyrocketed from 49 percent of the electorate in 1980 to 53 percent. Since then women have been at least 52 percent of the voters in each presidential election.

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“Without question, women’s political power is growing at a faster rate than is noticeable to the eye,” Smeal said.

In 2006, another major milestone was achieved. Rep. Nancy Pelosi was named the first female speaker of the House. While historic, Smeal noted that iconic magazines Time and Newsweek never put Pelosi on their covers. She points out that when Rep. John Beohner was elected speaker four years later, he graced both covers.

While 63 of 142 countries have had a woman leader, according to the World Economic Forum, but the U.S. is not one of them.

As she sometimes reminds the nation, Clinton’s nomination on Thursday will break the highest glass ceiling yet in American politics — leaving only a woman in the Oval Office remaining as the final hurdle.