As part of Niantic’s extensive Pokémon GO Summer Tour 2018, the second Pokémon GO Fest is set to take place on July 14 and July 15 in Chicago, Illinois, with tickets available from tomorrow, May 11, at 9 a.m. PDT. While Pokémon GO Fest 2018 will take place over the course of a weekend, participants will only be able to interact with the Pokémon habitats within the park for a single day. According to developer Niantic, it is illegal to resell Pokémon GO Fest 2018 tickets:
It is illegal to resell tickets in Illinois. Ticket holders who attempt to resell tickets or attend multiple days will be in violation of the Pokémon GO Fest 2018 Event Terms and Conditions, and run the risk of having their access to the event denied.
Source: Official Pokémon GO blog