The monthly Architecture Billings Index (ABI) came in at a score of 50.9 in April, down 3.4 points from March's 54.3, the AIA announced today.

The ABI is a leading economic indicator of construction activity in the U.S., and reflects a nine- to 12-month lead time between architecture billings and construction spending nationally, and regionally, as well as by project type. A score above 50, as seen in April, represents an increase in billings from the previous month, while a score below 50 represents a contraction.

The new project inquiries index—the most reliable indicator of future billings—declined slightly in March, which makes April's 3.4 dip in billings unsurprising. However, April's score of 50.9 still marks an increase in design services, as well as the third consecutive month of growth since January's marginal decline. Billings will likely continue to increase in May, given that the new project inquiries index increased 0.4 points in April to 60.2.

“Probably even better news for the construction outlook is that new project work coming into architecture firms has seen exceptionally strong growth so far this year,” said AIA chief economist Kermit Baker, Hon. AIA, in a press release. “In fact, new project activity has pushed up project backlogs at architecture firm to their highest level since the design market began its recovery earlier this decade.”

After a decline last month that ended five consecutive months of growth, the design contracts portion of the index increased 0.9 points, from March's score of 52.3, to a score of 53.2.

Regional billings, which, unlike the national score, are calculated as a three-month moving average, increased in three of four regions in April. The South experienced the biggest rebound, growing 1.3 points to 55.3 from March's reading of 54.0. Billings increased marginally in the West and the Northeast, growing 0.9 points and 0.5 points, respectively, to scores of 50.9 and 50.7. While billings in the Midwest decreased by 0.2 points during April, the region stayed in positive territory with a solid score of 53.3.

Architecture billings in the commercial/industrial sector posted a score of 52.4 in April, a 2.1 point gain from March's reading of 50.4. Billings in the institutional sector also increased during April, moving up 1.4 points from March's score of 52.6, to a score of 54.1. (Results of the sectors and regions are calculated as a moving average of the past three months.)