Thumb Score: +9 United Airlines have round trip airfares travelling from Chicago (ORD) to Cancun Mexico (CUN) for $231, nonstop. These are basic economy fares that allow a personal item. There is no seat selection, no carry-on bag and no change. If you are travelling with children, you will be seated together as per UA's policy. Travel Availability:Departs ORD: Aug 13, 18-20, 23-27; Sept 2-3, 9-10, 16-17, 23-24, 29-30; Oct 1, 7, 27-29; Nov 3-5, 10-12, 18 Returns: No Aug; Sept 6, 11-12, 18-20, 26; Oct 2-3, 10, 17, 23, 29-31; Nov 1, 5-7, 13-15