The U.S. construction spending rose to the highest in almost three years in September, propelled mainly by growth in private building activities, the Department of Commerce reported on Thursday.Construction spending was estimated at a seasonally adjusted annual rate of 851.6 billion U.S. dollars in September, up 0.6 percent from the revised 846.2 billion dollars in August and 7.8 percent from the level a year ago, the department said in a report. In September, spending on private construction was at a seasonally adjusted annual rate of 580.5 billion dollars, 1.3 percent above the revised August figure. The estimated seasonally adjusted annual rate of public construction spending was 271.1 billion dollars, 0.8 percent below the revised August reading. The U.S. housing market is struggling for a turnaround about 6 years after the bubble burst. Although recent sales and prices indicators were mainly upbeat, many economists believe that the housing sector still has a long way to go before a full recovery.