Over the past several months, I've noted how Ameristar Casinos (NASDAQ:ASCA) is the market leader in all four riverboat casino markets in which it competes. The stock has doubled over the past year (and just about quadrupled off its lows last February), yet remains more than reasonably priced, making one wonder why.

Here's a question to start with: Does Ameristar really have a sustainable competitive advantage?

Last month, in Those Pennies Add Up, we discussed one of the main differences between Ameristar and its key competitors. Backing out the take from penny and nickel slots, revenues for Ameristar and top competitor Harrah's Entertainment (NYSE:HET) look identical in both the St. Louis and the Kansas City markets.

The difference is that Ameristar has a lot more penny and nickel slots, made possible by its early adoption of cashless slots available from the likes of International Game Technology (NYSE:IGT), Alliance Gaming (NYSE:AGI), and WMS Industries (NYSE:WMS). Basically, Ameristar has capitalized on a trend and captured a first mover advantage, which should prove valuable wherever it is cheaper to retain a patron than to acquire a new one.

In the end, however, Ameristar's competitors simply could and probably will just add more penny and nickel slots themselves. So, how long does this advantage last? Or does it even matter? I suspect the answer to both is "only a little."

A classy brand and non-gaming amenities have helped give Ameristar the edge in head-to-head battles so far, but any such competitive advantage means less the greater the distance between competitors. Over the long haul, Ameristar's value may be tied more closely to the limited prospects for new competition than any specific competitive edge.

Give us your take on the Ameristar Casinos discussion board.

Fool contributor Jeff Hwang owns shares of Ameristar Casinos and International Game Technology.