Odaily News U.S. economic growth retreated slightly last month, according to a monthly index released Thursday. Americans are watching who will become the next president. The Chicago Fed said its national activity index fell to -0.28 in September from -0.01 in August. A reading above zero indicates that economic growth is improving on average. Meanwhile, the three-month moving average of the index fell to -0.19 from -0.14, further indicating that economic activity is generally weak ahead of the uncertain presidential election in early November. (Jinshi)