WASHINGTON (AP) — Dorothy Irene Height, a pioneering voice of the civil rights movement whose activism stretched from the New Deal to the election of President Barack Obama, died Tuesday. She was 98.

Height, who marched alongside Martin Luther King Jr. and led the National Council of Negro Women for 40 years, was known for her determination and grace — as well as her wry humor. She remained active and outspoken well into her 90s and often received rousing ovations at events around Washington, where she was easily recognizable in the bright, colorful hats she almost always wore.

Height died at Howard University Hospital, where she had been in serious condition for weeks.

In a statement, Obama called her ‘‘the godmother of the civil rights movement’’ and a hero to Americans.

‘‘Dr. Height devoted her life to those struggling for equality … and served as the only woman at the highest level of the civil rights movement — witnessing every march and milestone along the way,’’ Obama said.

Vice President Joe Biden said Height was one of the first people to visit him when he first took his seat in the Senate in 1973.

‘‘She remained a friend and would never hesitate to tell me or anybody else when she thought we weren’t fighting hard enough,’’ he said.

Height’s was the second death of a major civil rights figure in less than a week. Benjamin L. Hooks, the former longtime head of the National Association for the Advancement of Colored People, died Thursday in Memphis at 85.

Former Labor Secretary Alexis Herman, a close friend who has spoken for Height’s family and called Height her mentor, said funeral arrangements were pending.

Height received two of the nation’s highest honors: the Presidential Medal of Freedom in 1994 and the Congressional Gold Medal in 2004.

In awarding the congressional medal, then-President George W. Bush noted that Height had met with every U.S. president since Eisenhower, and ‘‘she’s told every president what she thinks since Dwight David Eisenhower.’’

In a statement Tuesday, Bush hailed ‘‘her grace and her determination. Our nation will never forget Dr. Heights efforts to make America a more compassionate, welcoming and just society.’’

Secretary of State Hillary Rodham Clinton and former President Bill Clinton, in a joint statement, said, ‘‘Our nation is poorer for her loss but infinitely richer for the life she led, the progress she achieved and the people she touched.’’

Height was born in Richmond, Va., before women could vote and when blacks had few rights. Her family moved to the Pittsburgh area when she was 4. Distinguishing herself in the classroom, she was accepted to Barnard College but then turned away because the school already had reached its quota of two black women. She went on to earn bachelor’s and master’s degrees from New York University.

As a teenager, Height marched in New York’s Times Square shouting, ‘‘Stop the lynching.’’ After earning her degrees, she became a leader of the Harlem YWCA and the United Christian Youth Movement of North America, where she pushed to prevent lynching, desegregate the armed forces and reform the criminal justice system.

She traveled to Holland and England as a U.S. delegate to youth and church conferences, and in 1938 was one of 10 young people chosen by Eleanor Roosevelt to spend a weekend at the first lady’s Hyde Park, N.Y., home preparing for a World Youth Conference at Vassar College.

One of Height’s sayings was, ‘‘If the time is not ripe, we have to ripen the time.’’ She liked to quote 19th century abolitionist Frederick Douglass, who said the three effective ways to fight for justice are to ‘‘agitate, agitate, agitate.’’

In the 1950s and 1960s, she was the leading woman helping King and other activists orchestrate the civil rights movement, often reminding the men heading not to underestimate their female counterparts.

Height was on the platform at the Lincoln Memorial, sitting only a few feet from King, when he gave his famous ‘‘I have a dream’’ speech at the March on Washington in 1963.

‘‘He spoke longer than he was supposed to speak,’’ Height recalled in a 1997 Associated Press interview. But after he was done, it was clear King’s speech would echo for generations, she said, ‘‘because it gripped everybody.’’

She lamented that the feeling of unity created by the 1963 march had faded, that the civil rights movement of the 1990s was on the defensive and many black families still were not economically secure.

‘‘We have come a long way, but too many people are not better off,’’ she said. ‘‘This is my life’s work. It is not a job.’’

When Obama won the presidential election in November 2008, Height told Washington TV station WTTG that she was overwhelmed with emotion.

‘‘People ask me, did I ever dream it would happen, and I said, ‘If you didn’t have the dream, you couldn’t have worked on it,’’ she said.

Height dedicated most of her adult life to the National Council of Negro Women, where she first worked under her mentor, Mary McLeod Bethune, who founded the group. Height took over in 1957 and led it until 1997, fighting for women’s rights on issues such as equal pay and education. She developed programs such as ‘‘pig banks’’ to help poor rural families raise their own livestock, and ‘‘Wednesdays in Mississippi,’’ in which black and white women from the north traveled to Mississippi to meet with their Southern counterparts in an effort to ease racial tensions and bridge differences.

To celebrate Height’s 90th birthday in March 2002, friends and supporters raised $5 million to enable her organization to pay off the mortgage on its Washington headquarters on Pennsylvania Avenue, just a few blocks from the White House. Herman said Height ‘‘believed very strongly that we as black women deserved to be on this corridor of power.’’