24 (from 5 confederations) were the number of teams who competed in US Open . 18 events were there in US Open . The official site of US Open is chicagomarathon.com . 11 from 2 nations were the competitors in US Open . Georgia Dome,New York City, New York,,United States were the venues of US Open . US Open was founded on 1884; 135 years ago (1884)
The sport US Open has more than24 contenders  from more than 4 nations