WASHINGTON — When Barbara A. Mikulski first stepped onto the Senate floor in 1987, she saw only one other female senator. They were required to wear skirts and were prohibited from using the male-only gym.
But as the retiring Maryland Democrat prepares to relinquish the title of "dean of the Senate women," she leaves a political environment that is fundamentally changed — from access to the treadmills to the possibility that a woman could ascend to the presidency.
The number of women serving in Congress has increased from 25 to 104 since 1987, and research indicates that female candidates now are just as likely to raise money, capture media attention and get elected as their male counterparts.
"The Senate, certainly, has changed," said Republican Sen. Susan M. Collins of Maine. First elected in 1996, she's now one of 20 female senators.
At the same time, advocates are troubled by a deep enthusiasm gap that has slowed the pace of gains among women at some levels. The proportion of women serving in state legislatures, for instance, has remained essentially stagnant, at just over 20 percent, since the mid-1990s.
And while the number of women in the Senate has grown, they still represent a smaller share of the body than in the U.S. population at large. Women hold just two committee chairs in the new Republican-controlled Senate and only one in the House.
"There has been tremendous progress," said Debbie Walsh, director of the Center for American Women and Politics at Rutgers University. But "I wouldn't want it to sound as though we're post-gender, that there is no issue here, that the problem is solved."
Mikulski, who waited until her fifth term before she was given her first committee chairmanship — she took over the Appropriations Committee in late 2012 — believes that significant work remains.
The first female Democrat elected to the Senate in her own right, Mikulski has campaigned for other Democratic women across the country for years. And she founded the bipartisan, closed-door dinners of female senators that have long been a Washington institution.
"Now we're going to go for the big enchilada, which is Hillary," said Mikulski, who announced last week that she would not seek re-election in 2016.
She has been an enthusiastic supporter of Hillary Clinton, having served as national co-chair of her campaign for the Democratic presidential nomination in 2008. And she is backing Clinton in her potential 2016 race, even as former Maryland Gov. Martin O'Malley considers a run for the nomination against her.
Mikulski bristles at the notion that the country is approaching an environment in which gender no longer matters.
"Whenever you have a minority status in our society, it's like, 'Oh, why should that count?'" she said. "Well, it does count."
She noted that the election of President Barack Obama did not eliminate racism: "You look around at our country and you tell me if race doesn't matter."
But in some ways, analysts say, gender matters less in politics than it used to. Jennifer Lawless, who heads the Women & Politics Institute at American University, said her research shows that gender does not seem to have been particularly relevant in elections for about the past 20 years.
Of Maryland's 10 representatives in Congress, only two are women: Mikulski and Rep. Donna Edwards of Prince George's County. That share — 20 percent — is about average; women make up 19.4 percent of Congress.
But several women in the state point to a burgeoning farm team, and a coordinated effort — influenced by Mikulski — to change the numbers. Women are increasingly running for state and local office, they say. Baltimore Mayor Stephanie Rawlings-Blake is the second woman in a row to hold that job. And the state ranks seventh in the nation in the number of women serving in the legislature, according to the Center for American Women and Politics.
"There is no reason to sit around wringing our hands thinking that it's bad to be a woman in politics," said Martha McKenna, a Democratic operative in Washington with deep ties to Maryland. "We're laying the groundwork for something that's going to be very significant."
McKenna chairs a group called Emerge Maryland, launched in 2012 to encourage and train Democratic women to run for office.
She said Mikulski cut the group one of its first checks.
Another measure of progress is the number of women who could step up to try to replace Mikulski in the Senate. At least five have publicly expressed interest, including Rawlings-Blake and former Lt. Gov. Kathleen Kennedy Townsend.
So far, only one candidate has formally announced a campaign — Rep. Chris Van Hollen, a Montgomery County Democrat. Already he has secured an endorsement from Senate Democratic leader Harry Reid, an indication that some in the party hope to avoid a bruising primary. Others have embraced the idea of a large, diverse pool of candidates.
Edwards, who said she is days away from making a decision on whether to enter the race, said it's important that a woman win Mikulski's seat. If elected, Edwards would also be the first black woman to represent the state.
"Maryland needs that kind of inspiration," Edwards said. "When you go into classrooms, all the girls know Barbara Mikulski."
Collins remembers meeting Margaret Chase Smith, the Maine Republican who was the first woman to serve in both the House and the Senate. Smith didn't discuss her gender when they met.
For Collins, she didn't have to.
"As someone who had just turned 18, when I left her office my reaction was that it opened my eyes to the fact that a woman could do anything," Collins said. "So, I don't think you have to talk about your gender for gender to be an influential factor."
Collins would later serve with Republican Sen. Olympia J. Snowe, making Maine one of the few states that has been represented in the Senate by two woman at once.
"We will get to the day — and I want us to get to the day — when gender is not an issue," Collins said. "But right now, there is still a sense of pride when another woman makes it to the top ranks."