On 13 April, 1904 congress passed an act that read in part:
“The secretary of the treasury shall, upon the request of the Lewis and Clark Centennial and American Pacific Exposition and Oriental Fair Company, cause to be coined at the mints of the United States not to exceed 250,000 gold dollars, of legal weight and fineness, to be known as the Lewis and Clark Exposition gold dollar, struck in commemoration of said exposition".
Which became the authorization for the second commemorative gold dollar (the first being the 1903 Louisiana Purchase dollars). The coins were struck in both 1904 and 1905, but sales were underwhelming in both years. Initially 25,000 coins were struck in 1904 with an additional 28 held for assay, but at the end of the year 15,003 of these were returned to the mint to be melted. 1905 followed a similar patter with 35,041 struck but 25,000 eventually melted leaving the net mintage in each year just a bit over 10,000 coins.
The design, executed by Charles Barber is extremely pedestrian, and includes a portrait of Meriwether Lewis on the obverse (so identified because it bears the date) and a portrait of William Clark on the reverse. The inscription on the obverse which runs the entire length of the rim includes the date and “Lewis-Clark Exposition Portland ORE”. The Reverse is equally plain with the inscription “United States of America” across the top and “One Dollar” across the bottom. The two Inscriptions are separated by dots.