There are
1,520 mi
from Rapid City, SD to Eureka, CA
That's the driving distance. It would take 1 day 3 hours to go from Rapid City, South Dakota to Eureka, California.
The flight distance (direct flight from Rapid City, SD to Eureka, CA) is 1,087.96 mi.
1,520 mi = 2,446.18 kms