The housing market continued to show strong signs of recovery, with residential real-estate prices rising an average of 2 percent in August in 20 key markets.

The S&P/Case-Shiller index released today showed the biggest year-to-year gain since July 2010. In July, the index was up 1.2 percent.

Just three cities of the 20 posted negative annual returns in August: Atlanta at -6.1 percent, New York at -2.3 percent and Chicago at -1.6 percent, Case-Shiller said in a statement.

"Home prices continued climbing across the country in August," David M. Blitzer, chairman of the Index Committee at S&P Dow Jones Indices, said in a statement. "Nineteen of the 20 cities and both Composites showed monthly gains in August. Seventeen cities and both Composites posted positive annual returns in August 2012. In 18 cities and both Composites annual rates improved in August versus July."

"The sustained good news in home prices over the past five months makes us optimistic for continued recovery in the housing market," Blitzer said.

August 2012 20 City Real Estate Price Index One-Month Change/One-Year Change

=============================== US Composite-20 0.88%/-1.76% ----------- Detroit 2.27% 7.58% Phoenix 1.76% 18.77% Atlanta 1.75% -6.12% Las Vegas 1.55% 0.90% Los Angeles 1.29% 2.15% Minneapolis 1.19% 7.44% Washington DC 1.08% 4.32% Cleveland 1.00% 1.13% Miami 0.95% 6.66% San Diego 0.87% 1.89% Chicago 0.71% -1.63% New York 0.71% -2.28% Boston 0.69% 1.73% Charlotte 0.56% 2.80% Denver 0.52% 5.53% Portland 0.49% 3.60% San Francisco 0.47% 5.30% Tampa 0.45% 4.19% Dallas 0.12% 3.59% Seattle -0.06% 3.36%