The Architecture Billings Index (ABI) dipped in January after a strong showing in December. The American Institute of Architects (AIA) reported the January ABI score was 49.5, down from 55.6 the previous month.

This score reflects a minor decrease in design services (any score above 50 indicates an increase in billings). The new projects inquiry index was 60.0, up from a reading of 57.6 the previous month.

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

“This small decrease in activity, taking into consideration strong readings in project inquiries and new design contracts, isn’t exactly a cause for concern,” says AIA chief economist Dr. Kermit Baker. “The fundamentals of a sound nonresidential design and construction market persist.”

Here are the key January ABI highlights:

Regional averages: South (54.2), Northeast (53.0), Midwest (52.4), West (48.8).

Sector index breakdown: institutional (54.6), commercial/industrial (53.4), mixed practice (48.1), multi-family residential (48.1).