Interstate 505

Interstate 505
I-505 highlighted in red
Route information
Auxiliary route of I-5
Maintained by Caltrans
Length	32.99 mi[1] (53.09 km)
Existed	1977–present
NHS	Entire route
Major junctions
South end	I-80 in Vacaville
Major intersections	SR 128 near Winters SR 16 near Madison
North end	I-5 near Dunnigan
Location
Country	United States
State	California
Counties	Solano, Yolo
Highway system
Interstate Highway System Main Auxiliary Suffixed Business Future State highways in California Interstate US State Scenic History Pre‑1964 Unconstructed Deleted Freeways
← SR 480 → I-580

Interstate 505 (I-505) is a north–south auxiliary Interstate Highway in the Sacramento Valley in Northern California. It is a spur auxiliary route of I-5 that runs from near Dunnigan south to I-80 in Vacaville. I-505 is primarily a rural Interstate, but travels through Vacaville and the city of Winters. The highway is the primary route connecting the San Francisco Bay Area and the northern Sacramento Valley, bypassing Sacramento and its attendant city traffic. Thus, it is a major route for travelers heading directly from the San Francisco Bay Area to the Shasta Cascade and the Pacific Northwest.

Power lines connecting Path 15 to Path 66 follow the highway for a while, until one heads northeast and the other northwest.