San Francisco and Northwestern Railway (SF&NW) was an Atchison, Topeka and Santa Fe Railway subsidiary formed in 1903 to connect Humboldt Bay to the Santa Fe rail system.

Subsidiary California Midland Railroad was formed in 1902 to extend the line up the Van Duzen River to Carlotta.

SF&NW acquired the Eel River and Eureka Railroad, its subsidiary California Midland, and the Pacific Lumber Company rail lines in 1903.

Purchase of the California and Northern Railway in 1904 gave SF&NW a 50-mile (80 km) main line from Arcata to the Eel River upstream of Scotia.

Santa Fe's distinctive circled cross herald appeared on the Eureka Depot.