From Minneapolis to Washington, D.C., marchers noticed the change, and wondered what it meant that so many white Americans were showing up for the cause of justice for black Americans.

“I was shocked to see so many white kids out here,” said Walter Wiggins, 67, as he sat near the heart of the protests in Washington last week. Mr. Wiggins, a retired federal worker, who is black, remembered attending the 1963 March on Washington and other civil rights events with his parents. “Back then it was just black folks.”…

White protesters made up 61 percent of those surveyed in New York over the weekend, according to the researchers, and 65 percent of protesters in Washington. On Sunday in Los Angeles, 53 percent of protesters were white.

It is not just protests. White Americans are going through a wave of self-examination, buying books about racism, talking to black friends, and arguing within their own families. Still, how much of this translates into broader change remains to be seen.