The Rev. Joseph E. Lowery, a lieutenant to the Rev. Dr. Martin Luther King Jr. who helped organize a pivotal moment in the civil rights movement — the bus boycott in Montgomery, Ala. — and who gave the benediction at President Barack Obama’s inauguration more than half a century later, died on Friday at his home in Atlanta. He was 98.

The Martin Luther King Jr. Center for Nonviolent Social Change announced his death on Twitter.

Even before Rosa Parks refused to give up her seat on a Montgomery bus on Dec. 1, 1955, Mr. Lowery had successfully campaigned to integrate buses in Mobile, Ala., where he was a young Methodist minister. After Ms. Parks’s action, he huddled with Dr. King and other Alabama ministers to oversee a 381-day boycott of Montgomery’s segregated buses.

In November 1956, the Supreme Court ended racial segregation on buses in Montgomery and, by extension, everywhere else.

Mr. Lowery was at Dr. King’s side almost until the day of his assassination in April 1968. At Dr. King’s request, he presented the demands of voting-rights marchers from Selma, Ala., to Gov. George C. Wallace in 1965. Mr. Lowery also helped found the Southern Christian Leadership Conference, Dr. King’s signature organization, and led it for 20 years, from 1977 to 1997.