The portion of Business Loop I-80 through West Sacramento and Sacramento that meets Interstate standards is designated by the Federal Highway Administration as I-305. This includes the entire segment concurrent with U.S. 50, as well as the first 1.6 miles of California 51 north to near C Street. Caltrans does not recognize Interstate 305 as an official state route designation since it is not defined in the Streets and Highways Code. This designation is not marked, and it ends at the point where the elevated 29-30 viaduct descends near C Street. The American River bridge and the remainder of the Business Loop I-80 freeway northeast of there, including the Marconi Curve, are not part of I-305 as the route does not meet Interstate standards. A new alignment was previously proposed to replace this stretch. It was cancelled by the City of Sacramento in 1979.

Actions by the FHWA on May 15, 1980 resulted in the relocation of I-80 to bypass Sacramento along what was previously Interstate 880. The Capital City Freeway portion was dropped from the Interstate system east of the exchange with I-5 and SR 99 and reclassified as State Route 51 (FAI 51). The freeway west from SR 99 to I-80 at West Sacramento was established as FAI 305. FAI 305 was then renumbered as a westward extension of U.S. 50, and all of the former I-80 alignment was resigned as Interstate Business Loop 80. FAI 305 was never signed as Interstate 305. However, the FAI designation remains in place to this day. Per the FHWA Interstate Route Log and Finders List, I-305 is 6.00 miles long, ending at an arbitrary point along the Capital City Freeway near C Street, where the planned new alignment of I-80 was proposed to tie in from the north.1

According to Joe Rouse, Interstate 305 is a federal designation used for funding purposes only. Caltrans refers to it internally as state route 50, and it is primarily signed as U.S. 50 between West Sacramento and the Elvas Freeway, and as Business Loop I-80 northeast from there. The I-305 portion of U.S. 50 is often referred to as the WX, Camellia City Viaduct, or simply as Highway 50. There have never been any plans to sign Interstate 305 in the field, and the California Streets and Highways Code omits the route as well.


  1. The Dwight D. Eisenhower System of Interstate and Defense Highways: Part V - Interstate Withdrawal-Substitution Program: Withdrawal of I-80 -- Sacramento, California.

    Page Updated 06-20-2018.