Project Blue Book Case #2025. On September 2, 1952, a bright object was observed over Chicago — the fourth Blue Book unknown from America's second city (joining Cases #1344, #1382, and #2962). No major American city outside the New Mexico nuclear corridor produced as many repeat unknowns as Chicago.
Chicago's four cases spanned from June through September 1952, covering the entire arc of the great wave. The city's world-class airspace — Midway was still the world's busiest airport — made each unknown all the more remarkable. Every object in Chicago's sky was tracked, logged, and identified as a matter of routine. These four were the exceptions.
The case was classified "Unknown."