The American Institute of Architects' architecture billings index, a measure of demand for nonresidential design services, rose in December for the 10th month in the past year.

The index is a leading indicator of development activity, providing a glimpse of construction nine to 12 months before builders report it.

December's index was 52.2, up from November's 50.9. The index uses 50 as flat activity, and anything above that is an increase in demand.

As for broader economic implications, the AIA's chief economist, Kermit Baker, says the last stalwart resisting the postrecession construction boom has been public buildings.

"Particularly encouraging is the continued solid upturn in design activity at institutional firms, since public sector facilities were the last nonresidential building project type to recover from the downturn," Baker said in a statement.

The U.S. saw more months of growth than contraction in 2014, with architectural billings dipping only two months out of 12.

Regional averages provide a more nuanced story. The strongest December growth was concentrated in the South, 56.8, and West, 52.9. Meanwhile, the Midwest hovered slightly above neutral with a score of 50.8, and the Northeast pulled down the national average, with a reading of 45.5 that indicated a decrease in demand.