“The ultimate measure of a man is not where he stands in moments of comfort and convenience, but where he stands at times of challenge and controversy. The true neighbor will risk his position, his prestige, and even his life for the welfare of others.” - Martin Luther King, Jr.

From the streets of Selma to the walls of the White House, Martin Luther King, Jr. worked tirelessly for the civil rights of African-Americans, and ultimately human rights for everyone. Enjoy this slideshow of photographs that document his influence on four presidential administrations.