The American Institute of Architect’s index of billings increased slightly in March to 51.7 from 50.4 in February. The index serves as an indicator of future construction activity, with a score above 50 indicating an increase in billings. Midwest architects recorded a score of 51 for March. “Business conditions at Iowa architecture firms are remaining quite healthy across the state,” Jessica Reinert, executive director of AIA Iowa, said in a release. “The institutional and commercial sectors are seeing the largest amount of growth and the new project inquiries index continues to go up.”