Architecture firm billings growth slowed in September but remained positive for the twelfth consecutive month, according to a new report today from The American Institute of Architects (AIA).

AIA’s Architecture Billings Index (ABI) score for September was 51.1 compared to 54.2 in August. However, continued strength in new projects coming into architecture firms points to billings growth in the coming months.

“Similar to the strong conditions we’ve seen nationally, architecture firms located in the Midwest and Southern regions of the country continued to report very strong billings in September,” said AIA Chief Economist Kermit Baker, Hon. AIA, PhD. “However, billings were soft at firms located in the Northeast again, where they have declined or been flat for the entire year so far.”

Key ABI highlights for September include:

-Regional averages: Midwest (59.7), South (54.1), West (53.1), Northeast (46.6)

-Sector index breakdown: institutional (55.1), multi-family residential (54.9), mixed practice (53.4), commercial/industrial (50.8)

-Project inquiries index: 58.8

-Design contracts index: 54.1

Regional and sector categories above are calculated as a three-month moving average, whereas the national index, design contracts, and inquiries are monthly numbers.

More information on AIA’s ABI is available online.