US home prices posted the largest annual gain since 2006 in March in fresh evidence that the housing recovery is gaining traction, according to a closely watched report released Tuesday. The S&P/Case-Shiller 20-city price index rose a non-seasonally adjusted 1.4 percent in March from February, which had a modest 0.3 percent gain. On a 12-month basis, home prices were up 10.9 percent in March, the largest increase since 2006, and all 20 cities in the index posted gains for the third month in a row. \"Other housing market data reported in recent weeks confirm these strong trends: housing starts and permits, sales of new homes and existing homes continue to trend higher,\" said David Blitzer, chairman of the Index Committee at S&P Dow Jones. Blitzer noted other factors that suggested the housing recovery still had a way to go, including a number of homes still in foreclosure and homes being snapped up by investors to rent. In the 20 largest US urban areas, the average home price was back to its late 2003 levels. Fifteen of the 20 cities showed a monthly gain, up from 11 in February. San Francisco prices jumped the most, up 3.9 percent.