MOUNTAIN VIEW — Silicon Valley’s job growth has returned to dot-com boom levels and San Francisco has emerged as a major new tech hub. But good times have not returned for all area residents and ethnic groups.

Those are among the findings released Tuesday from the 2013 Silicon Valley Index, a closely watched annual study produced by San Jose-based Joint Venture Silicon Valley and the Mountain View-based Silicon Valley Community Foundation.

“Employment growth in Silicon Valley is impressive, very impressive,” said Russell Hancock, president of Joint Venture Silicon Valley. “Some might even say the job growth is cause for euphoria.”

Last year, the nine-county Bay Area added about 92,000 jobs, according to the study. Of that total, Silicon Valley — defined as Santa Clara and San Mateo counties — accounted for 46 percent, or 42,000 jobs.

“This is prodigious job creation,” Hancock said. “The growth is crazy and it’s getting crazier.”

Both he and Stephen Levy, director of the Palo Alto-based Center for Continuing Study of the California Economy and an adviser for the report, said Santa Clara County now is above its job totals of the dot-com boom.

Recent Bay Area job growth goes well beyond social media, software, the Internet and other technology industries, showing that the recession is clearly over for the region.

“The tech phenomenon is rippling into other categories,” Hancock said. Construction is one of the fastest-growing industries in the region, according to the report.

The study also found that San Francisco has emerged as a prominent contributor to what is known as Silicon Valley.

“For a long time we thought of San Francisco as an old-line town — banking, legal, retail, real estate,” Hancock said. “Now it’s tech, software, media, social networks, the Web.”

And that means the definition of Silicon Valley is expanding, the researchers said.

“We have two very dynamic entities, San Jose and San Francisco,” said Doug Henton, CEO of San Mateo-based Collaborative Economics, which did the primary research for the Silicon Valley Index. “They are very complementary to each other.”

During 2012, Santa Clara and San Mateo counties increased their combined job totals by 3.6 percent, while San Francisco grew its job totals by 3.7 percent.

Emmett Carson, CEO of Silicon Valley Community Foundation, said San Jose and San Francisco “are becoming the bookends with many tech companies in between.”

Despite the sturdy job gains, the report found that the upswing in employment and wages has not benefited Bay Area residents equitably.

“Income growth in Silicon Valley is uneven,” it said. “The gap between high and low income earners is increasing.”

What’s more, certain ethnic groups appear to have been left behind by Silicon Valley’s current surge in hiring and rising wages.

Between 2009 and 2011, per capita income levels increased for whites, Asians and certain other groups. But blacks and Latinos suffered financial erosion. Income levels fell 18 percent among African-Americans and by 5 percent among Latinos, according to the report, but it offered no explanation for the declines.

“Silicon Valley is two valleys,” Hancock said. “There is a valley of haves, and a valley of have-nots.”

Contact George Avalos at 408-373-3556 or 925-977-8477. Follow him at Twitter.com/george_avalos.