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The TSA security checkpoint hours are below: T1, A Gates: 4:00 a.m. – 8:30 p.m. Serving Air Canada, Delta, United and charter flights. T1, C Gates: 3:45 a.m. – 9:30 p.m. Serving American, Air Choice One, Alaska, Cape Air and Frontier. https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.flystl.com/faq&ved=2ahUKEwiIxL2ajdfgAhUGbawKHZY_By8QFjACegQIDxAO&usg=AOvVaw0-U4AelH7K5-hMsimCD8Il
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