The Sacagawea golden dollar has been the dollar coin for the United States since the year 2000, when it replaced the Susan B. Anthony dollar coin. Sacagawea was a Shoshone woman who was instrumental to the success of the Lewis and Clark expedition. A teenager at the time, she accompanied the expedition during the years 1804 through 1806. The design of the obverse of the Sacagawea dollar, by Glenna Goodacre, portrays her in three-quarter profile, carrying her infant son, Jean Baptiste, on her back. No one actually knows what Sacagawea looked like, as there are no existing portraits of her, so Goodacre used a contemporary Shosone woman named Randy'L He-Dow Teton as a model. The reverse, designed by Thomas D. Rogers, Sr., shows a flying eagle surrounded by 17 stars that represent the 17 states in the union at the time. The Sacagawea dollar is golden in color, although there is no actual gold in the composition. It is composed of a pure copper core, surrounded by an alloy of copper, zinc, manganese and nickel. One of the complaints about the Susan B. Anthony dollar was that it was too much like a quarter for practical use in circulation; the golden color and plain edge of the Sacagawea dollar represent attempts to forestall similar confusion. The coin was legislated into existence by the United States Dollar Coin Act of 1997, with the hopes that the public would use it in daily transactions. It didn't. Although still minted, by 2002 the coin was effectively out of circulation. Like any other coin, the Sacagawea dollar can be collected. The most valuable examples are extremely high grade coins minted for circulation.