July 18 (UPI) -- Rep. John Lewis, a civil rights leader who worked to desegregate the Deep South and served in the House of Representatives for more than three decades, has died. He was 80.
His death comes several months after he revealed doctors were treating him for Stage 4 pancreatic cancer.
House Speaker Nancy Pelosi confirmed his death in a statement Friday.
"Today, America mourns the loss of one of the greatest heroes of American history: Congressman John Lewis, the Conscience of the Congress," she wrote.
"In the Congress, John Lewis was revered and beloved on both sides of the aisle and both sides of the Capitol. All of us were humbled to call Congressman Lewis a colleague, and are heartbroken by his passing. May his memory be an inspiration that moves us all to, in the face of injustice, make 'good trouble, necessary trouble.'"
President Donald Trump ordered flags be flown at half staff in Lewis' honor.
Born Feb. 21, 1940, near Troy, Ala., Lewis grew up the son of sharecroppers with several siblings. He attended segregated schools, but learned of civil rights activism by listening to radio broadcasts of the Rev. Martin Luther King Jr.
He joined the movement, organizing lunch counter sit-ins in Nashville and participating in Freedom Rides as a student at Fisk University. Lewis was severely beaten and arrested for his activism.
Former President Barack Obama said Lewis made civil rights "his life's work."
"He loved this country so much that he risked his life and his blood so that it might live up to its promise," he said.
"And through the decades, he not only gave all of himself to the cause of freedom and justice, but inspired generations that followed to try to live up to his example."
Lewis served as the chairman of the Student Nonviolent Coordinating Committee from 1963 to '66 and was known as one of the so-called Big Six leaders of the Civil Rights Movement. In 1963, he was a keynote speaker at the March on Washington, the same event at which King gave his "I Have a Dream" speech.
He organized voter registration drives, community action programs and participated in the historic Selma to Montgomery march in which demonstrators were attacked by Alabama state troopers in what came to be known as "Bloody Sunday."
In 1977, President Jimmy Carter put him in charge of ACTION, a federal volunteer agency.
Lewis began his political career in 1981 when he was elected to the Atlanta City Council. Five years later, he was elected to his first term in the House of Representatives, representing Georgia's 5th Congressional District, which includes parts of Fulton, DeKalb and Clayton counties.
Lewis faced a runoff in his first Democratic primary against Georgia state Rep. Julian Bond, who led the first primary election with 47 percent of the vote. In the runoff, Lewis pulled off an upset, defeating Bond 52 percent to 48 percent. He won the general election with an overwhelming 75 percent of votes.
He's won re-election in the district 16 times, only once dropping below 70 percent of the vote in the general election.
In Congress, Lewis served on the House Ways and Means Committee and was chairman of the panel's subcommittee on oversight. He also was the senior chief deputy whip for the Democratic Party in the House.
He co-authored the National Book Award-winning graphic novel memoir trilogy MARCH with Andrew Aydin and illustrator Nate Powell. The series also was a New York Times bestseller and has been used in school circula to teach the Civil Rights Movement.
Lewis also has been the recipient of a number of awards, including the Medal of Freedom, presented by former President Barack Obama, the Lincoln Medal, the John F. Kennedy Profile in Courage Lifetime Achievement award and the Martin Luther King Jr. Non-Violent Peace Prize, among others.
Lewis is survived by his son, John-Miles Lewis. His wife of 44 years, Lillian, died in 2012.