Keywords: 100th Anniversary Professional Baseball 6c 1969 issue U.S. stamp.jpg en 100th Anniversary Professional Baseball - 1869-1969 - 6-cent 1969 issue U S stamp 1969-09-24 U S Postal Service; National Postal Museum http //arago si edu/category_2034303 html 100th Anniversary Professional Baseball Issue Bureau of Engraving and Printing Designed by Alex Ross other versions PD-USGov Stamps of the United States 1961-1970 Commemorative stamps of the United States 1969 in Major League Baseball 1969 stamps of the United States Baseball on stamps |