Unelected, but expected to act as befits her "office," the first lady has what Pat Nixon called "the hardest unpaid job in the world." Michelle Obama championed military families with the program Joining Forces. Four decades earlier Pat Nixon traveled to Africa as the nation's official representative. And nearly four decades before that, Lou Hoover took to the airwaves to solicit women's help in unemployment relief. Each first lady has, in her way, been intimately linked with the roles, rights, and responsibilities of American women. Pursuing this connection, First Ladies and American...