Though the souvenir half dollar struck for the 1892-93 World's Columbian Exposition, held in Chicago, had initiated the US commemorative coin program, commemorative medals were still popular with collectors in the 1890s. As such, not all groups seeking a US Mint-struck commemorative piece approached Congress with a request for a coin. Case in point, the 1898 Trans-Mississippi and International Exposition Association.
The group looked to stage an exposition "for the exhibition of the resources of the United States of America and the progress and civilization of the Western Hemisphere, and for a display of the arts, industries, manufactures, and products of the soil, mine, and sea." The Exposition was to showcase "the great staples of the transmississippi region which contributes so largely to domestic and international commerce." (Quotations are from the medal's authorizing legislation.)
The Exposition was held in Omaha, Nebraska from June 1 to November 1, 1898.
Rather than seek a coin, the Association pursued a Mint-struck commemorative medal and a medal it could use as an award for winning exhibitors. Congress passed a bill in 1896 that sanctioned the Exposition, appropriated funds for it, called for the US Government to participate in it and for the Mint to strike the aforementioned commemorative and award medals; the bill was signed into law by President Grover Cleveland on June 10, 1896.
The Treasury Department had an exhibit in the US Government Building in which it struck the medals on a traveling US Mint press. In its advertising, the Association referred to the medals as "Souvenir Coins" and alerted visitors to the fact that they could "witness" their striking at the Exposition.
The obverse of the medal was advertised as a composite of "forty-eight beautiful young women, from the twenty-four Western States and Territories." The portrait was said to idealize "the highest type of Western young womanhood." The medal's reverse featured a Native American on horseback spearing a bison on the Western plains. (Quotations are from the Association's advertising sheet for the medals.)
Per the Association's flyer for the medal, it was struck on planchets that were the same size as the US gold double eagle (34 mm), and was available in gold ($20), silver ($1) and gold-plated bronze ($0.25). It should be noted that the original standard reference work that includes the medal (i.e., So-Called Dollars
by Harold E. Hibler and Charles V. Kappen) lists the medal in silver (HK-281), bronze (HK-282) and brass (HK-283) but not in gold or gold-plated. Have a look at the second example example of mine below; it is identified as a brass piece, but I think its appearance suggests it is gold-plated (based on comparisons to other Mint-struck pieces that are known to be gold-plated.) US Mint Press at ExpositionRead More: Commems Collection