To highlight what they say is a fresh attack on equal rights, U.S. civil rights campaigners are marching 1,385 kilometers from Selma, Alabama, to Washington, D.C.
After starting at the historic Edmund Pettus Bridge, the "40-day-and-40-night'' march is to end September 15.
To mark the start of the so-called "America's Journey for Justice'' Reverend Theresa Dear told the Montgomery Advertiser newspaper, "We are doing something of biblical proportions.''
More than 200 supporters are taking part in the first leg of a march that will be about 16 times the 54-mile distance covered by voting rights activists in 1965.
The rally, organized by the National Association for the Advancement of Colored People marks the 50th anniversary of the Voting Rights Act, which campaigners say is now under threat.
Activists say a 2013 Supreme Court decision has allowed some states to reverse some provisions of the Act.
The marchers sang as they crossed the Edmund Pettus bridge, where state troopers beat activists protesting about the death of a black man at the hands of a white police officer in March 1965.
That event, and a follow-up march from Selma to Montgomery led by Martin Luther King helped build momentum for Congress' approval of the Voting Rights Act that removed all barriers preventing African-Americans from registering as voters.
Organizers of this march also say the U.S. outcry following recent police killings, needs to be channeled into a long-term commitment to bring about change.
NAACP leader Cornell William Brooks told Reuters news agency, "We can continue to be serially outraged, or we can engage in an outrageously patriotic demonstration with a commitment to bringing about reform in this country."
In March, President Barack Obama visited Selma to pay tribute to the original marchers, calling them "heroes," but he said the fight against racism is not over.
He also condemned new attempts by state governments to restrict voting rights.
Some information for this report came from AP.