There are
2,084 mi
from Oshkosh, WI to San Marcos, CA
That's the driving distance. It would take 1 day 13 hours to go from Oshkosh, Wisconsin to San Marcos, California.
The flight distance (direct flight from Oshkosh, WI to San Marcos, CA) is 1,707.24 mi.
2,084 mi = 3,353.98 kms