Current Worldcons
2017 Worldcon in Helsinki, Finland
The above Worldcons have been selected. You can buy memberships from their websites.
San José, California will host the 2018 Worldcon. Details of the convention are available from their website.
Upcoming Worldcon Bids
The following groups are bidding to hold the 2019 Worldcon.
A full list of future Worldcon bids can be found here.