Rosie the Riveter is, I believe, the only icon on the history making women list. The rest of the women have all been flesh and blood. As far as icons of strong American women go, though, Rosie has to be #1.
At her most basic, Rosie represents the six million or so women who took to munitions and materials factories all over the United States during World War II. The idea of Rosie based on that of Michigan riveter Rose Will Monroe, who starred in a government promotional film encouraging women to support the war effort at home. Her most famous image, though, shown in the "We Can Do It!" Westinghouse poster, was based on another Michigan riveter, Geraldine Doyle. Originally, the "We Can Do It!" poster was not meant to represent Rosie the Riveter at all, but the connection between the two was made in the mid-1940s.
Though women's entry into manufacturing during World War II did for a time change their entire position in the United States economy, it was not the force of economic equilibrium it is sometimes painted to be. Women welders and riveters usually made significantly less money than did their male counterparts, and when the war ended, most of them left manufacturing and many of them left the workforce altogether.
Since the 40s, and especially after the feminist movement of the 1970s, Rosie's image has stood in not just for women's entrance into the work force in larger numbers, but for a general feeling of women's empowerment in the United States. The National Organization for Women (NOW) sells t-shirts with her image and the words "NOW Let's Get to Work!" Her image is seen not only telling women that we can do it, but also saying "feminist" and even "Up yours, George!" In 1999, her image was on a 33-cent stamp, and it is featured widely on t-shirts, hats, buttons, etc.