At the Chicago Marathon on Sunday, October 11, 2026, many participants noticed sometimes dramatic differences between the official distance of 42,195 km and that displayed by their GPS watch. In particular, the skyscrapers in the city centre, which disrupt satellite signals, sometimes with consequences for race management.
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At the Chicago Marathon on Sunday, October 11, 2026, many participants noticed sometimes dramatic differences between the official distance of 42,195 km and that displayed by their GPS watch. In particular, the skyscrapers in the city centre, which disrupt satellite signals, sometimes with consequences for race management.