Though a monthly index of billings to architecture firms dropped in March, designers continue to see increased activity, especially in the Midwest, according to a release from the Iowa chapter of the American Institute of Architects. On a month-to-month basis, inquiries for design services dropped to an index reading of 51.9, down from 54.9 in February. Any reading above 50 indicates an increase in billing requests. On a three-month moving average, architects in the Midwest reported an index reading of 53.9.  "The industry has generally been improving over the last several months and projects being brought to the state keep the profession hopeful," AIA Iowa Executive Director Jessica Reinert said in the release. "A slight ease of pace in the growth in March is not alarming to the Midwest with regional averages remaining above average." Requests for design services typically precede construction activity by six months to a year.