Facebook creator Mark Zuckerberg and his wife, Priscilla Chan, were the most generous American donors of 2013 according to the Chronicle of Philanthropy. Zuckerberg and his wife donated 18 million shares of Facebook stock to a Silicon Valley nonprofit in December. The stock was valued at about $992 million. The Chronicle of Philanthropy called the donation the largest charitable gift on record last year, making them America's most charitable philanthropists. TheStreet's Brittany Umar details other high-ranking American donors of 2013.