There are two powerful forces at work in this historic south Texas town, economic growth and the rising political power of Mexican-Americans, and they have come together in a mayoral election that will set the tone for San Antonio in the decade ahead.

San Antonio, a diverse and charming city, is the nation's ninth largest, with the Alamo its most endearing symbol and a shaded Riverwalk in the heart of downtown its loveliest attraction. Long dominated by Anglo business interests, it nonetheless receives much of its flavor from a rich Hispanic heritage.

Like most cities in the Southwest, San Antonio is in the middle of an economic boom, spurred by a sharp increase in population and a desire to attract new industry, and the optimism here is irrepressible. But with 54 percent of its population of Hispanic origin, the city is under increasing pressure to distribute the benefits of that economic growth more widely in the community.

That is what Saturday's mayoral election is about, and while ethnic politics are not an explicit issue, they are the underlying theme. But there is more than simply ethnic politics at work here, and to many voters the election has become a symbol of San Antonio past and San Antonio future.

The two candidates are Henry Cisneros, a 33-year-old, Harvard-trained urban planner, and John Steen, a 59-year-old businessman and civic leader. Both are members of the City Council, and seem to agree on most of the issues affecting the city. But Cisneros is an activist, while Steen sees a need for less government.

If elected, Cisneros would become the first Mexican-American mayor of a major American city, but both candidates have attempted to avoid polarizing the community on that issue. "This is not an ethnic race," said Cisneros, who runs as a champion of economic development and a supporter of nuclear power and avoids many of the planks of the traditional minority platform.

The fact that race is not the dominant issue is seen by people here as evidence that the era of confrontation politics between minorities and the Anglo establishment has ended, and, if elected, Cisneros is expected to try to put together a governing coalition that includes blacks, browns, labor and developers.

It is Cisneros' ties to the developers that has become one of the major issues in the campaign. Steele, aided by the Washington consulting firm of Bailey and Deardourff, put together a negative ad campaign attacking Cisneros for accepting financial support of these "power brokers" and suggesting a deal had been made.But the ad campaign has tarnished Steen's reputation as a kind and decent man.

Steen says he should be elected because of his long experience in business and civic affairs. "My opponent," he said, "has not lived that long, he's never really owned a business. I've been in the trenches."

Cisneros counters that he as the better opportunity to unite the city and has proven he can attract new jobs to San Antonio."I was preaching economic growth six years ago," he said.

The presence of six other candidates on the ballot Saturday, including the son of a Mexican-American who once ran for mayor, could force a runoff between Steen and Cisneros.