All these years later, these two men, Robinson and King, still have the power to inspire and enlighten. Their lives are intertwined. Robinson was an inspirational figure to King as he endured unspeakable cruelty, pain and loneliness after breaking baseball's color line in 1947.
Almost as important to King was how Robinson responded to the hatred and threats. He simply played baseball and grudgingly acknowledged that doing anything else would have inflamed the situation.
Later in Robinson's life, though, as he saw churches bombed and civil rights workers murdered, he said that King's pleas for a nonviolent movement had been a challenge.
"He's a constant marvel to me," Robinson said of King.
At that point in Robinson's life, long after his baseball career, he was registering black voters and raising money to replace bombed and burned-out churches. He said King's admonition "to love this kind of person" who would bomb churches hadn't been easy.
King often said that Robinson -- and other African Americans who followed him into Major League Baseball -- helped make racial fairness easier for many white Americans to accept. Seeing Robinson playing alongside such Brooklyn Dodgers icons as Pee Wee Reese and Pete Reiser was so unsettling to many people that it forced them to see the world differently than they'd ever seen it.
Shortly before his assassination in 1968, King told former Dodgers pitcher Don Newcombe, "You'll never know how easy you and Jackie and [Larry] Doby and [Roy Campanella] made it for me to do my job by what you did on the baseball field."
"Imagine," Newcombe told the New York Post's Peter Vecsey in 2009, "here is Martin getting beaten with billy clubs, bitten by dogs and thrown in jail, and he says we made his job easier."
They changed the world an inch or two at a time, and history will draw a line from Robinson and Hank Aaron to King and Barack Obama.
When Robinson began to speak out on civil rights late in his baseball career, King called him "a pilgrim that walked in the lonesome byways toward the high road of freedom. He was a sit-inner before sit-ins, a freedom rider before freedom rides."
Robinson became one of the most popular and eloquent speakers in the civil rights movement and would end many of his speeches with this:
"If I had to choose tomorrow between the Baseball Hall of Fame and full citizenship for my people, I would choose full citizenship time and again."
For men like Kendrick, 51, this is a holiday that resonates on a couple of levels. He grew up in Crawfordville, Ga., with an older brother, Fred, who was active in the civil rights movement.
"I'm a young kid out there marching and singing because everyone else was," Kendrick said. "Only later do you understand what it means. You grew up not questioning why you had to go in through the back door. That's just what you did. That's where your friends were. As you get older, you get more rebellious."
Sometimes his brother took him along on the 90-mile trip to Atlanta. All these years later, it was his mother's sack lunches that still have meaning.
"The meaning of those lunches didn't resonate with me until much later," he said. "All I knew is that we were going to have some good eating. Later, you look back and realize she made those lunches because she didn't feel comfortable with us stopping along the way."
At some point in his life, Robinson became one of his heroes, then Buck O'Neil. And the threads began to connect.
This weekend the Negro Leagues Baseball Museum hosted a youth basketball tournament to commemorate MLK Day. Before those kids left, though, they learned about Robinson and O'Neil and what they contributed to racial fairness.
"When someone gives of himself for the greater good, it's one of the most incredible things anyone can do," Kendrick said. "Whether it's Dr. King or Jackie Robinson, it's about the sacrifices they showed the world. All roads lead back to right here. If not for the Negro Leagues, we don't get Jackie Robinson. The work we do every single day is about civil rights and the sacrifices and work those men and women did to make life better for others. Dr. King's work was done selflessly. He -- and they -- knew they weren't going to be the ones to benefit. That's the core of the story."