California State Route 51

Interstate 80 Business
Capital City Freeway
Business 80 highlighted in red
Route information
Defined by
Maintained by Caltrans
Length:	14.50 mi (23.34 km)
Existed:	1979 by FHWA 1983 (from I-80) by Caltrans – present
Major junctions
West end:	I-80 in West Sacramento
	I-5 in Sacramento US 50 / SR 99 in Sacramento
East end:	I-80 / SR 244 in Sacramento
Location
Counties:	Yolo, Sacramento
Highway system
Interstate Highway System Main Auxiliary Suffixed Business Future State highways in California Interstate U.S. State Pre-1964 History Unconstructed Deleted Freeway Scenic ← US 50 SR 52 →

Interstate 80 Business, called the Capital City Freeway in its entirety and also known as Business 80, is a business loop of Interstate 80 through Sacramento. It is also informally referred to as "Cap City Freeway" and "Biz 80". Although signed as a business loop the route is actually two connected segments. The western segment is signed as U.S. Route 50 and carries the unsigned designation of Interstate 305. The unsigned designation of the eastern segment is State Route 51. The entire route is a freeway, and carried mainline Interstate 80 through Sacramento until the early 1980s. Portions of the eastern half were initially grandfathered into the Interstate Highway system; however, plans to upgrade or realign this portion to meet Interstate Highway standards were cancelled. As such, the I-80 designation through Sacramento was moved to a northern bypass of the city that had previously been signed Interstate 880 (which was later reassigned to what had been State Route 17 between Oakland and San Jose), and the old route of I-80 through downtown was given the current business loop designation.