Map of central California with SR 104 highlighted in red
|Defined by Streets and Highways Code § 404|
|Maintained by Caltrans|
|Length||36.04 mi (58.00 km)|
|West end||SR 99 near Galt|
|East end||SR 49 in Sutter Creek|
State Route 104 (SR 104) is a west–east state highway in the U.S. state of California that runs from the Central Valley to the Sierra Foothills. It connects State Route 99 near Galt to State Route 49 in Sutter Creek via the city of Ione. It is known as Twin Cities Road from its western terminus up until just before Ione. West of the SR 104/SR 99 interchange, Twin Cities Road continues to Interstate 5 and then eventually end at State Route 160 north of Walnut Grove.
The route begins in Galt in Sacramento County at SR 99. It then heads eastward, forming the northern boundary of the city of Galt. The route turns northeast, passing through Herald, near Rancho Seco Nuclear Generating Station and on to the community of Clay before entering Amador County. It then continues past Mule Creek State Prison and begins a short overlap with SR 124 in Ione. Afterwards, it exits the town and has another overlap with SR 88, where it goes through the community of Sunnybrook. Its eastern terminus is at SR 49 in Sutter Creek.
Except where prefixed with a letter, postmiles were measured on the road as it was in 1964, based on the alignment that existed at the time, and do not necessarily reflect current mileage. R reflects a realignment in the route since then, M indicates a second realignment, L refers an overlap due to a correction or change, and T indicates postmiles classified as temporary (for a full list of prefixes, see the list of postmile definitions). Segments that remain unconstructed or have been relinquished to local control may be omitted. The numbers reset at county lines; the start and end postmiles in each county are given in the county column.
|Galt||0.00||CR E13 (Twin Cities Road) – Walnut Grove||Continuation beyond SR 99|
|0.00||SR 99 – Sacramento, Stockton||Interchange; west end of SR 104|
|Ione||R5.77||SR 124 north (Plymouth Highway) / Shakeley Lane – Plymouth, Placerville||West end of SR 124 overlap|
|R5.96||SR 124 south (Church Street) – Stockton||East end of SR 124 overlap|
|SR 88 west / Jackson Valley Road – Stockton||West end of SR 88 overlap|
|SR 88 east – Martell, Jackson||East end of SR 88 overlap|
|Sutter Creek||10.07||SR 49 – Sutter Creek, Jackson||East end of SR 104|
|10.07||Ridge Road||Continuation beyond SR 49|
|1.000 mi = 1.609 km; 1.000 km = 0.621 mi|
- Indicates that the postmile represents the distance along SR 88 rather than SR 104.
- California Department of Transportation (July 2007). "Log of Bridges on State Highways". Sacramento: California Department of Transportation.
- California Road Atlas (Map). Thomas Brothers. 2008.
- Federal Highway Administration (March 25, 2015). National Highway System: California (North) (PDF) (Map). Scale not given. Washington, DC: Federal Highway Administration. Retrieved October 1, 2017.
- Natzke, Stefan; Neathery, Mike & Adderly, Kevin (June 20, 2012). "What is the National Highway System?". National Highway System. Washington, DC: Federal Highway Administration. Retrieved July 1, 2012.
- California Department of Transportation. "State Truck Route List". Sacramento: California Department of Transportation. Archived from the original (XLS file) on June 30, 2015. Retrieved June 30, 2015.
- California Department of Transportation, All Traffic Volumes on CSHS, 2005 and 2006
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