Yes, Swissair operated to San Francisco. However the ZRH
flights were cut due to economical reasons.
There were several discussions on this forum about the SWISS flights to Los Angeles too. Although the route has potential it is losing a lot of money so I don't see LX
to expand service to California soon...
You are right, the A-310 operated to Africa but also to North America (BSL
was operated by A-310s in an early stage).
I hope this helps!