Jul 12, 2018 - 11:58 PM
St Louis is now served by Basel tram route 3 which was recently extended to St Louis, re-establishing a tramway link closed on the 1950s. It is a Basel city tram route but Swiss Travel Pass is not valid as it crosses the border. You would need to buy a short hop ticket from St Louis to the first stop on Swiss territory.
Alternatively take the train from St Louis to Basel SNCF/SBB, again a local ticket would be needed for that.
If you are staying in St Louis (suspect you've realised it's a cheap way to stay 'in Switzerland') for some days, you will soon get used to what ticket to buy and where the ticket machines are situated.