The AIA’s monthly Architecture Billings Index (ABI) came in at a score of 51.1 in September, marking the 12th consecutive month of gains. 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, regionally, and by project type. A score above 50, as seen in September, represents an increase in billings from the previous month, while a score below 50 represents a contraction.