The mourners came from every corner of the city, thousands filing beneath the soaring vault of Riverside Church to honor Hector Figueroa, among the country’s most dynamic and influential labor leaders. Mr. Figueroa, president of 32BJ S.E.I.U., a New York local of the Service Employees International Union, died of a heart attack on July 11 at 57. His memorial service on Wednesday was part funeral and part political rally, a rousing celebration of the working people and human values that Mr. Figueroa championed.

S.E.I.U.’s ranks consist of the army of low-paid service workers — security officers, window cleaners, health care aides — vital to the American economy and American life. At the church, janitors and fast-food workers, some of them in uniform, sat alongside the governor of New Jersey, the mayor of New York and the New York State attorney general. Generations of the city’s political elite grieved beside generations of labor leaders, Mr. Figueroa’s family and neighbors and the workers he organized and led, many of whom took time off from their jobs.

Grown men — large men — wept, their broad shoulders locked side-by-side in the pews.

The stone apse, long a cradle for progressive politics in New York, rang with the sounds of Puerto Rican folk music, African-American gospel choir and joyous laughter, as speakers told stories about Mr. Figueroa’s passionate persistence.

Donna Hampton, an airport worker, said the work she had done with Mr. Figueroa to organize her formerly nonunion colleagues — who won a $19 minimum wage last year — had changed her life. “I’m sure we’ve all lost one along the way,” Ms. Hampton said, breathing deeply. “But I’m here to tell you, this one really hurts.”