WASHINGTON (AP) — President Barack Obama is urging Americans on the 45th anniversary of the Voting Rights Act to honor the legacy of those who helped make the law possible by exercising the rights they fought hard to guarantee.

The 1965 law guaranteed blacks the right to vote. Its passage was spurred by the unprovoked and bloody attack by Alabama state troopers on peaceful marchers crossing the Edmund Pettus Bridge from Selma to Montgomery on March 7, 1965.

Obama says the law marked the culmination of decades of work by such civil rights activists as Martin Luther King Jr. and Rosa Parks to fulfill America’s promise of equality. He says all Americans should exercise their right to vote and continue working to promote equality.