Profile of Sacagawea with her infant son, Jean Baptiste Charbonneau being carried on her back.

Sacagawea (1788-1812) was a Lemhi Shoshone woman who helped the Lewis and Clark Expedition achieve each of its chartered mission objectives exploring the Louisiana Purchase. With the expedition, between 1804 and 1806, she traveled thousands of miles from North Dakota to the Pacific Ocean, established cultural contacts with Native American populations, and researched natural history.

The Lewis and Clark Expedition, also known as the Corps of Discovery Expedition, was the first American expedition to cross what is now the western portion of the United States, departing in May 1804, from near St. Louis making their way westward through the continental divide to the Pacific coast.

Engraver: Glenna Goodacre (GG)

The reverse design features a Native American and horse in profile with horses running in the background, representing the historical spread of the horse.

American Indians maintained widespread trans-continental, inter-tribal trade for more than a millennium. This cross-continental trade infrastructure culminated in the construction of the modern-day interstate highway system. Trading routes centered on Zuni Pueblo in the Four Corners region of the southwest and the Mojave bead route to the California coast were incorporated into the Old Spanish Trail (now a National Park Service historic trail). The Old Snake Trade Route connected the pueblos of New Mexico north to the Mandan villages in the present-day Dakotas, branching to the west in present-day Wyoming and reaching the Columbia River at The Dalles in Oregon.

Of all the goods traded throughout the continent, the horse, spread by Indian tribes through Native American trade routes, is perhaps the most significant. Thanks to inter-tribal trade, horses had crossed the Rio Grande by 1600. The horse's spread in Native American hands was so prodigious that it became the primary means of transportation and the nucleus of the ranching economy already underway in the western territories. In the south, the Caddo trade center became a major entry point for the horse. Trade up the Old Snake Route brought horses as far north as the Mandan in North Dakota, who supplied them to the Lakota and Blackfeet. A parallel inter-mountain route brought horses to the northwest. By the time Lewis and Clark wintered with the Mandan in 1803, they encountered a well-established horse culture.

Designer: Thomas Cleveland (TS)
Engraver: Phebe Hemphill (PH)

Inscribed along the edge of the coin is the year of minting or issuance of the coin, the mint mark, and also the legend "E Pluribus Unum" (Latin for "Out of many, one").

Position A: edge lettering reads upside-down when Sacagawea's portrait (obverse) faces up.
Position B: edge lettering reads normally when Sacagawea's portrait (obverse) faces up.