Why are first ladies so important in the United States despite the fact that they are unpaid and have no official responsibilities? There are several reasons, but the most important reason is they are role models for other women in the United States.

Theodore Roosevelt called the White House the "bully pulpit", as he believed it was the perfect platform for promoting social causes and ideals and all the first ladies since "Lady Bird" Johnson in the 1960s have used the bully pulpit to advance social causes.

"Lady Bird" Johnson was an environmental pioneer. Pat Nixon promoted volunteerism. Betty Ford was an early proponent of women's rights. Rosalyn Carter an advocate for the rights of people with mental health problems. Nancy Reagan used her time to fight drug abuse. Barbara Bush promoted literacy in general, while Laura Bush focused her attention on childhood literacy. Hillary Clinton was a child advocate and author. Michelle Obama is currently leading a fight against childhood obesity, a problem of epidemic proportions in the US.

They were all effective to varying degrees inside the US, but few have made an impression internationally.

Once in a blue moon, though, first ladies can project the US' soft power beyond its borders. In this regard, Jacqueline Kennedy was head and shoulders above the rest. Although she wasn't an actress, model or singer, she was a fashion and cultural icon who charmed people wherever she went. She was half of the couple who for a thousand days gave the US what appeared at the time to be an idyllic period. Because of them, many people never felt prouder to be a citizen of the United States.

While in the White House, she gave a televised tour of her newly renovated historic home. More than a half-century later this black-and-white performance that featured a cameo by her husband is still a tour de force of soft power projection.