Even without Las Vegas-style slot machines, Oklahoma's Indian gaming industry is growing at an almost unmatched pace, a national study indicates.The number of electronic gambling machines nearly doubled between 2001 and 2003, as did the revenue those machines produced.

Gaming at 73 Oklahoma locations earned tribes $465.9 million, up from $245.7 million two years earlier, according to a report by the Analysis Group.

"The increase there has been enormous. It's definitely one of the fastest-growing states both in terms of machines and in revenue," study manager Alan Meister said.

Despite the advances, Oklahoma tribes captured less than 3 percent of America's Indian gaming revenues last year, the national consulting firm reported.

Oklahoma's rural market, its lack of destination casino resorts and its lack of Class III gambling are the reasons, Meister said.

An upcoming statewide election could help Oklahoma's tribes reduce the gap.