Basically the whole country.
https://www.sbb.ch/en/station-services/railway-stations/trafimage/trafimage-karten.htmlThe GA travelcards, Half-Fare cards, and other passes are valid on most forms of transport.
https://www.sbb.ch/content/dam/sbb/de/pdf/abos-billette/abonnemente/ga/karte-geltungsbereich-ga-halbtax_en_barrierefrei.pdf.download.pdfThere are also multiple local networks, that offer tickets and passes including networks of bordering countries (e.g. Liechtenstein, Austria, Germany, France). The tickets are most often zone-based.
