Business Loop I-5 - Dunsmuir

Historic U.S. 99 referenced in place of Business Loop I-5 in Dunsmuir, CA — Business Loop I-5 through Dunsmuir begins at Exit 729, but it is signed from the northbound mainline instead as Historic U.S. 99. Once on Dunsmuir Avenue, the business route is well signed with reassurance shields. 05/25/08

Former Business Loop I-5 sign in Dunsmuir, CA — Long since removed, this Business Loop "I-I-5" shield was posted along Dunsmuir Avenue south of the Sacramento River and north of Downtown Dunsmuir. Photo by Jerry Mullady (03/99).

Business Loop I-5 north on Historic U.S. 99 in Dunsmuir, CA — Reassurance marker posted along Dunsmuir Avenue north for Business Loop I-5. The 3.6 long mile route follows Historic U.S. 99. 05/25/08

According to the California State Highway System Signing Log (October, 1991), Business Loop I-5 in Dunsmuir runs from "Interstate 5 and South Dunsmuir undercrossing over Florence Avenue to Interstate 5 and North Dunsmuir undercrossing and Siskiyou overcrossing." Totaling 3.7 miles in length, the business route follows Dunsmuir Avenue in close proximity to I-5 from Exit 729 north to Exit 732.

Dunsmuir Avenue was marked with historic U.S. 99 signs as early as the late 1990s. These were taken down eventually, but replacement signs were installed for the route by 2008. A handful of Business Loop I-5 markers line the avenue otherwise.

Updated August 4, 2026