I found the following information in a book about the Western Pacific, the parent company of Sacramento Northern:

Oakland-Lafayette - Abandoned February, 1957 (track removal began April 3, 1957)
Lafayette-Walnut Creek - Abandoned 1958
Walnut Creek-Concord - Abandoned 1964
Concord-Clyde - Abandoned 1974 (last train left Concord on 12/12/1973)
Clyde-Port Chicago - Abandoned 1997
Port Chicago-West Pittsburg - ***Still In Service***
West Pittsburg-Pittsburg - Abandoned September, 1994
West Pittsburg-Montezuma - Abandoned 1955
Montezuma-Dozier - Sold to BAERA in January, 1993
Dozier-Libfarm - Abandoned December, 1987
Libfarm-Saxon - Abandoned October, 1980
Saxon-Arcade - Abandoned 1962
Arcade-Riverview - Abandoned October, 1980
Riverview-West Sacramento - (recently abandoned - unknown date, but after 2000)
West Sacramento-Broderick - ***Still In Service***
Broderick-Mikon - ***Still In Service***
Haggin Yard (Sacramento)-Globe - Abandoned 1953
Globe-Rio Linda - Abandoned February, 1972
Rio Linda-Sankey - Abandoned May, 1985
Sankey-Catlett - Abandoned January, 1972
Catlett-East Nicolaus - Abandoned 1965
East Nicolaus - Pearson - Abandoned October, 1958
Pearson-Alicia - ***Still In Service***
Alicia-Oliver - Abandoned 1955
Oliver-Marysville - Abandoned 1925 (switch installed to WP bridge 1925)
Marysville-Colusa Junction - Abandoned 9/15/2004 (last train was 12/18/2002)
Colusa Junction-Live Oak - Abandoned January, 1986
Live Oak-Peachton - Abandoned November, 1971
Peachton-Oroville Junction - Abandoned 1966 (trackage rights on SP from Live Oak to Durham)
Oroville Junction-Durham - Abandoned August, 1971
Durham-Chico - Abandoned January, 1986

If you need dates for the branch lines, I have those also. By the way...passenger service ended in 1941, not the 1950's.

--James