What jersey number has been retired across all of MLB in honor of Jackie Robinson?

Lou Gehrig's disease, which ended his career, is medically known as what? Which player broke MLB's color barrier on April 15, 1947? For which team did Jackie Robinson play? Which player was the first Black player in the American League, in 1947? In what year was Jackie Robinson's number 42 retired by all MLB teams? Which Pirates star died in a 1972 plane crash while delivering aid to Nicaragua? MLB's annual award for a player's community service is named after which player? Which legendary Negro Leagues pitcher made his MLB debut at age 42 in 1948?