The gain contrasted with analysts' forecasts of a 1.5% drop in spending, but there were signs of weakness in the Commerce Department's report, which showed spending reached $970 billion at an annual rate in March.
February spending was revised downward to a 1% drop from the 0.9% decrease originally reported. March's spending rate was 11.1% below that in March 2008.
Private construction slipped 0.1%, mostly from a 4.2% decrease in residential building, which makes up more than one-third of the category. The spending rate of $258 billion was the lowest in nearly 12 years.
However, public construction, which had tapered off in winter, increased 1.1% in March and 1.3% in February. Most of the boost came from state and local governments where spending rose 1.3% in March.
The economic recovery bill passed in February included billions of dollars for capital projects, and this could be the first indication some of the funding has reached the U.S. economy.
The $309 billion rate of public construction spending was 2.6% higher than in March 2008.
