Interstate 805
Auxiliary Interstate Highway in San Diego County, California, United States
Interstate 805 (I-805) is a major north–south auxiliary Interstate Highway in Southern California. It is a bypass auxiliary route of I-5, running roughly through the center of the Greater San Diego region from San Ysidro (part of the city of San Diego) near the Mexico–U.S. border to near Del Mar. The southern terminus of I-805 at I-5 in San Ysidro is less than 1 mi (1.6 km) north of the Mexican border. I-805 then traverses the cities of Chula Vista and National City before reentering San Diego. The freeway passes through the San Diego neighborhoods of North Park, Mission Valley, Clairemont, and University City before terminating at I-5 in the Sorrento Valley neighborhood near the Del Mar city limit.
Planning for I-805 began in 1956, and the route was officially designated in 1959 before it was renumbered in the 1964 state highway renumbering. Starting in 1967, the freeway was built in phases, with the northern part of the freeway finished before the southern part. I-805 was completed and open to traffic in 1975. Named the Jacob Dekema Freeway after the longtime head of the regional division of the California Department of Transportation (Caltrans), I-805 has been frequently cited for its complex engineering and architecture, including near I-8 on the Mission Valley Viaduct. Since then, several construction projects have taken place, including the construction of carpool lanes.
“Interstate 805” enters the record as auxiliary Interstate Highway in San Diego County, California, United States. Crown Archives preserves that source wording while asking what Interstate, Auxiliary and Highway can confirm, complicate or overturn.
Why this record matters
“Interstate 805” is worth following because a concise public description often conceals a longer documentary argument. Here, Interstate, Auxiliary and Highway provides the most credible route into that argument.
Maps, plans, fabric surveys and administrative records can establish how the site’s name, extent and function changed over time. The source revision retrieved here is dated Sep 16, 2026. The linked authority identifier is Q399988. 1 of 1 selected statements include explicit references; 0 carry qualifiers and 0 use preferred rank. The first chronological checks are 1956, 1959, 1964 and 1967.
A single description cannot reconcile every naming convention, rebuilding phase or administrative transfer associated with a place. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Treat names, boundaries and functions as historically changeable. Maps, plans, inventories and administrative records can clarify what the place meant at different dates.
- Historic place names
- Jurisdictional context
- Routes into maps and plans
Contemporary maps, plans, listed-building records, estate papers and the responsible local or national archive.
Three-step research path
- Establish the record: confirm the title “Interstate 805”, its source revision and the description used here.
- Expand the search: follow Interstate 805 primary sources, Interstate 805 archive and Interstate research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Interstate 805”?
- Which authority defined the place, boundary or structure at the relevant date?
- Which earlier names or jurisdictions may reveal additional records?
Search terms from this dossier
This entry incorporates text from “Interstate 805” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.