Led by growing demand for new schools, hospitals, cultural facilities and municipal buildings, the Architecture Billings Index (ABI) increased in May, following its second monthly drop this year.

As a leading economic indicator of construction activity, the ABI reflects the approximate nine to twelve month lead time between architecture billings and construction spending.

The American Institute of Architects reported the May ABI score was 51.9, up from a mark of 48.8 in April. This score reflects an increase in design services (any score above 50 indicates an increase in billings). The new projects inquiry index was 61.5, up from a reading of 60.1 the previous month.

“As has been the case for the past several years, while the design and construction industry has been in a recovery phase, we continue to receive mixed signals on business conditions in the marketplace,” said AIA Chief Economist Kermit Baker. “Generally, the business climate is favorable, but there are still construction sectors and regions of the country that are struggling, producing the occasional backslide in the midst of what seems to be growing momentum for the entire industry.”

Key May ABI highlights:

• Regional averages: South (54.6), Midwest (52.3), West (49.9) Northeast (45.2)

• Sector index breakdown: institutional (55.2), mixed-practice (52.5), commercial / industrial (48.3) multifamily (45.9)

• Project inquiries index: 61.5

• Design contracts index: 53.4.