The AIA’s monthly Architecture Billings Index stayed in positive territory for the third-consecutive month, posting a score of 50.6 in April, down slightly from March's reading of 51.9 and roughly on par with a year ago. The ABI is a leading economic indicator of construction activity in the U.S. reflecting the nine- to 12-month lead time between architecture billings and construction spending nationally and regionally as well as by project type. Any score above 50 indicates an increase in billings.

“Architects continue to report a wide range of business conditions, with unusually high variation in design activity across the major building categories,” AIA chief economist Kermit Baker, Hon. AIA, said in a press release.

Architecture firms surveyed for the index reported strong growth in design contracts, recording a score of 54.3 in April, the highest in eight months. “The strong growth in design contracts—the strongest score for this indicator since last summer—certainly suggests that firms will be reporting growth in billings over the next several months,” Baker said. Project inquiries, meanwhile, dipped to 56.9 in April.

All of the index's four U.S. regions—whose marks are measured as a three-month average—saw their billings increase in April. The Midwest reported the largest month-over-month gain, from 50.0 to 50.8. Close behind were the Northeast and West, notching up to 51.5 and 50.8, respectively. The South closed the month with a mark of 52.2, down 0.3 points from the average reported in March, but still an increase for the period.

Among the sectors tracked by the index, which are also calculated as three-month averages, multifamily residential led for the sixth-straight month with a reading of 53.7, followed by commercial/industrial at 52.0, mixed-practice at a break-even 50.0, and institutional at 49.0.