In 1803, Thomas Jefferson commissioned the Corps of Discovery, a small group of volunteers tasked with exploring the American West. The leaders of the expedition were Meriwether Lewis and William Clark, and the venture is more commonly known as the Lewis & Clark Expedition. The United States had somewhat inadvertently purchased a large claim from France, the Louisiana Purchase, and Lewis & Clark were some of the first Americans to explore these territories and the lands further west. They reached the Pacific Ocean near the mouth of the Columbia River in November 1804 and spent the winter there near present-day Astoria, Oregon. The expedition helped later American claims over the Oregon Country, which was also claimed by Great Britain until the Oregon Treaty of 1846.

Around the turn of the 20th century, a committee of Portland businessmen planned a large fair to commemorate the centennial of the Lewis & Clark Expedition and its influence on the development of Oregon. In 1904, they succeeded in obtaining $500,000 in federal funding. A provision in the legislation also authorized a gold dollar to help fund the Lewis & Clark Centennial Exposition. As was usual for this era, a sponsoring organization would purchase the coins from the government at face value and sell them to the public at a premium as a fundraising measure.

The design of the coin was left to longtime Chief Engraver Charles Barber. Unusually, each side of the Lewis & Clark dollar bears a portrait – Lewis on the obverse, Clark on the reverse (the prior is considered the obverse as it contains the date). It is the only such “two-headed” coin in the history of US coinage.

The organizers of the Lewis & Clark Exposition put famed numismatist Farran Zerbe in charge of sales and distribution efforts. However, the Lewis & Clark Exposition Dollar did not sell well. This was in large part due to the experience of the public in purchasing the Louisiana Purchase Exposition dollar, which was issued in 1903. Zerbe was similarly involved in the distribution of the Louisiana Purchase coin and struggled to justify its sale price of $3. By the time the Lewis & Clark dollar was issued, prices of the Louisiana Purchase dollar had declined precipitously from this level. The similar subject matter of both coins was another obstacle to marketing efforts. Coins were produced in both 1904 and 1905, but in the end, most Lewis & Clark dollars were returned to the Mint and melted.

Despite the failure of the coin, the Lewis & Clark Centennial Exposition was a success. Nearly 1.6 million people visited the Exposition, contributing to an economic boom in Portland. Unusually for large fairs of this era, the Lewis & Clark Exposition turned a profit for its investors.