Douglas Brinkley, a Rice University history professor and author, whose works include books about the late civil rights icons Rosa Parks and Dr. Martin Luther King Jr., discusses differences between the 1960s civil rights protests and those of today:

Then: Protests fueled by Christian credos with a soundtrack of gospel music and spirituals.

Now: “More raw anger" in the streets, but with hip hop and other current music as the soundtrack.

Then: Nonviolence. King once was punched in the face on stage, took the blows, and urged that the white man not be charged.

Now: Protesters more militant, “no one's going to tolerate a punch in the face” without responding.

Then: Black demonstrators supported by white people opposed to the Vietnam War.

Now: Black demonstrators supported by others frustrated by the pandemic and economy.

Then: Civil rights leaders felt the sympathy of Presidents Lyndon B. Johnson and John F. Kennedy.

Now: President Donald Trump “mimics the language” of '60s white supremacists about protesters.

Then: Activists such as three young men, two of them white, murdered 56 years ago this week in Mississippi's Freedom Summer, could suddenly disappear.

Now: Social media and cellphones provide quick calls for help; cell phone cameras can make police abuses “go viral.”