Although their billings declined in March, architects continue to see growing demand for design services across all regions of the U.S., according to the American Institute of Architects (AIA) Architectural Billing Index (ABI).

AIA reports the ABI score slipped from 54.9 in February to 51.9 in March, but notes that any score above 50 indicates increasing demand for design work. March marked the eighth consecutive month the index scored above 50.

“Business conditions in the construction industry have generally been improving over the last several months,” says AIA Chief Economist Kermit Baker.“But as we have continued to report, the recovery has been uneven across the major construction sectors, so it’s not a big surprise that there was some easing in the pace of growth in March compared to previous months.”

With a score of  54.6, the Northeast led all regions, followed by the Midwest (53.9), the South (53.6) and the West (51.9).

Among market sectors, multifamily residential fared best with a score of 56.9, its 11th  consecutive month above 50. Multifamily also has scored above 50 for the 25 of the past 30 months.

Commercial (53.5) was the second-strongest performer, followed by mixed practice (53.3) and institutional (50.6).

Although ABI's score for project inquires declined from 64.8 in February to 60.1 in March, inquiries have scored above 60 for three consecutive months and above 50 for more than four years.

As a leading economic indicator of construction activity, the ABI reflects the approximate nine- to 12-month lag time between architectural billings and construction spending.