April 15th is a pretty historic day in baseball history.
It is the anniversary of the day (April 15, 1947) that Jackie Robinson became the first African American to suit up and play for a Major League Baseball team, breaking the color barrier as a member of the Brooklyn Dodgers. Robinson was a Rookie of the Year and Most Valuable Player recipient, was an All-Star several times, and was inducted into the Baseball Hall of Fame in 1962. In 1997, his number 42 was retired across all major league teams.
Jackie Robinson was also known for his involvement in civil rights. Inspired by the March on Washington, Jackie and his wife Rachel Robinson organized a jazz concert in 1963 on the lawn of their home in Connecticut to raise bail money for jailed civil rights protesters, including Dr. Martin Luther King, Jr.
The first concert boasted jazz greats like Duke Ellington, Joe Williams, Ella Fitzgerald, Sarah Vaughan, and Dizzy Gillespie, and became an annual tradition. It was and is considered an honor for many musicians to play for the man who broke the baseball color barrier.
Jackie Robinson died in 1972, and the jazz concert became a annual fundraiser for the Jackie Robinson Foundation. The JRF provides college scholarships and mentoring to academically gifted minority students. The Foundation has supported over 1,200 Scholars who have maintained a 97% graduation rate, more than twice the national average for minority students.
In 2006, the event moved to the west coast and became known as Jazz on the Grass. Years after his death, jazz musicians continue to show their gratitude, by performing and helping raise money for causes that continue to open new doors.
Sources: http://www.jackierobinson.org/
http://groovenotes.org/2010/04/