Along with perms, mix tapes and denim jackets, the mid-1980s saw a rash of celebrity activism against hunger. From Band Aid to Live Aid, musicians around the globe lent their voices to raise money for famine-stricken Africa. After USA for Africa garnered $53 million with its 1985 supergroup hit “We Are The World,” the organization’s president, Ken Kragen, cast his charity attention homeward. Kragen proposed an audacious plan—called a “stunt” by United Press International—to raise between $50 million and $100 million for hungry and homeless Americans by enlisting 6 million people to form a coast-to-coast human chain on May 25,...