WASHINGTON — On Friday, the Showtime cable network is to air “Geraldine Ferraro: Paving the Way,” a documentary about her 1984 race for vice president. Although she was defeated, her candidacy was a seminal moment in politics that was validated by the subsequent leap in the number of women holding office.

In three decades, political women have gone from anomalies to mainstream, though they still are underrepresented. The odds are, in two years, the Democrats will nominate a woman for president, and there’s an even chance that the Republican candidate will choose a female running mate.

The best research on these issues is from the Center for American Women and Politics, a unit of the Eagleton Institute of Politics at Rutgers University.

When Ms. Ferraro was picked as Walter F. Mondale’s running mate, she was one of only 22 women among the 435 members of the House of Representatives. There were only two senators: Nancy Kassebaum and Paula Hawkins, both Republicans.