Former US president Bill Clinton and former Secretary of State Hillary Clinton in a joint statement, "We have lost a giant. John Lewis gave all he had to redeem America’s unmet promise of equality and justice for all, and to create a place for us to build a more perfect union together."
House Speaker Nancy Pelosi called Lewis "a titan of the civil rights movement whose goodness, faith and bravery transformed our nation."
Lewis was a protege of the Rev. Martin Luther King Jr., whom he met after writing to him when Lewis was just 18. He was the last surviving speaker from the 1963 March on Washington, having stood beside King when he made his "I Have a Dream" speech.
Lewis kept up the fight for civil rights and human rights until the end of his life, inspiring with others with calls to make "Good Trouble."
In 2016, Lewis led a "sit-in" by House Democrats to demand a vote on gun regulations. He made his last public appearance last month, as protests for racial justice swept the United States and the world.
Using a cane, Lewis walked with Washington mayor Muriel Bowser on a street by the White House that Bowser had just renamed Black Lives Matter Plaza. It had just been dedicated with a large yellow mural - large enough to be seen from space - reading "Black Lives Matter."
Tributes quickly began pouring in from other politicians, Lewis' fellow Democrats and Republicans.
The Republican majority leader of the US Senate, Mitch McConnell, said Lewis had a place "among the giants of American history" even before he was elected to Congress, noting his rise from a family of sharecroppers in segregated Alabama.
"The Senate and the nation mourn the loss of Congressman John Lewis, a pioneering civil rights leader who put his life on the line to fight racism, promote equal rights, and bring our nation into greater alignment with its founding principles," McConnell said.
"John Lewis was an icon who fought with every ounce of his being to advance the cause of civil rights for all Americans," said Senator Kamala Harris, the first African American to represent California in the Senate, on Twitter. "I'm devastated for his family, friends, staff - and all those whose lives he touched.