Historians like Ruck see Rickey's experiment, which opened the way for Robinson to break the color barrier with the Brooklyn Dodgers, as a trigger to a number of events that followed. It played a significant role, Ruck said, in fueling the move toward integration.
Yet perhaps no socio-political event in the first half of the 20th Century was as fraught with risk as this one.
"I don't see why a top-flight Negro ballplayer would be so anxious to play in the white leagues when he is doing so well in his own organization," Atlanta Journal sports editor Ed Danforth is quoted as saying at the time in historian Jules Tygiel's book "Baseball's Great Experiment: Jackie Robinson and His Legacy."
Even facing such intractable critics, black Americans and the black press had continued to call for integration -- but not just in sports. They argued that democracy wasn't a black-white issue; their issue became one of equality.
How do people who had long been viewed as inferior prove they are an equal? They needed a defining moment, an event in history that so crystallized their equality that nobody could dispute the matter.
On April 15, 1947, Robinson provided that defining moment. He would have much to prove.
In agreeing to Rickey's terms for integrating the game, Robinson, a bright, educated man, had to douse the competitive fires that raged inside him. He realized that Rickey had almost asked the impossible. It might have been easier altogether if Rickey had asked Robinson to stop breathing.
For how could he put his emotions in mothballs?
But Robinson knew that he must corral his rage for Rickey's experiment to succeed. Historians said the late '40s weren't the time for militancy, not if meaningful progress in race relations were to be made in America.
"Robinson created a sort of picture that all society should be integrated," said Titus Brown, a professor of history and African-American Studies at Florida A&M University. "That's why we could see a shifting and changing in society in the mid-1950s."
The success of the experiment put segregation under society's microscope, Brown said. It forced people to take a different look at race in America.
"Breaking the color barrier did say, 'Maybe it's not so bad that you can have an African-American athlete participate in the so-called American sport,'" Brown said. "I think people started to rethink it after they saw Robinson."
He suggested that President Harry S Truman's 1948 decree that integrated the Armed Forces might have been an outgrowth of the successful desegregation of baseball. Ruck said Truman, perhaps emboldened by Robinson, seemed to sense that, in an election year, he had plenty to gain from opening opportunities to blacks.
"It seems to me," Ruck said, "that when something happens in one area of American life and it happens smoothly -- maybe not from Jackie's point of view, because he had to deal with a lot -- then that just makes it easy for further change.
"In subtle, subconscious ways, it makes it easier for white people to accept black people and to hire black people in positions they had not been hired before."
Robinson also made it easier for blacks to stoke the fires for full equality. After Truman's decree in '48, the quest for equal rights gathered momentum.
Within a decade, the doctrine of "separate but equal," which had governed race relations in the United States since the dawn of the 1900s, gave way to the U.S. Supreme Court decision in Brown vs. the Board of Education of Topeka in 1954, which struck down one of the legal barriers that blacks had to hurdle.
Other changes would soon follow, and the civil rights movement quickened its pace from there as black stars like Monte Irvin, Larry Doby, Willie Mays and Don Newcombe continued to prove that they could compete and play alongside white ballplayers.
"If you break down barriers in one field, it directly impacts others, particularly economic, political and social," said Julius Thompson, a professor of history and black studies at the University of Missouri. "So for me, it had implications in all these other areas in advancing civil rights and general human rights in the United States and other countries."
Yet all of these socio-political advances came with struggles, Ruck said. The advances were never straightforward; they were never uniform across American society.
Ruck, Thompson and Brown said Major League Baseball, thanks to Robinson, had a profound influence on putting those changes in motion.
"But you've got to remember that Robinson was an exceptional player," Brown said. "So if he had been a failure, it would have impacted the way people viewed blacks, especially in the arena of baseball."