On Friday, Motley Fool Hidden Gems selection Ameristar Casinos (NASDAQ:ASCA) announced long-awaited plans for a $100 million expansion of Iowa's Ameristar Council Bluffs. Rather than replace the existing riverboat outright, Ameristar is opting to add space on a single floor to accompany the existing three-level riverboat.

Overall, the company plans to add 60,000 square feet to the facility, including 38,500 square feet of gaming space, more than doubling the casino's size. However, the expansion will add only 600 slot machines and 20 table games, including a poker room. That would give the property a rough total of 2,250 slot machines and 50 table games within 77,000 square feet of gaming space. The expansion also will feature an "elaborate central bar area" and two additional bars, a deli, a new 1,000-space parking garage (doubling covered parking space), and a new Star Club VIP lounge.

The expansion should once again make Ameristar Council Bluffs the biggest casino in its three-casino market. Harrah's Entertainment (NYSE:HET) owns the other two casinos -- the Horseshoe Council Bluffs racino and the Harrah's Council Bluffs riverboat. Last March, Harrah's introduced the rebranded and expanded Horseshoe property, with 1,900 slot machines and 62 table games in 68,000 square feet of gaming space. The Horseshoe has held the market-share lead ever since.

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Fool contributor Jeff Hwang owns shares of Ameristar Casinos. The Fool's disclosure policy wears a tux to the poker table.