Four Level Interchange
interchange in Los Angeles County, California, United States
The Four Level Interchange (officially the Bill Keene Memorial Interchange) is the first stack interchange in the world. Completed in 1949 and fully opened in 1953 at the northern edge of Downtown Los Angeles, California, United States, it connects U.S. Route 101 (Hollywood Freeway and Santa Ana Freeway) to State Route 110 (Harbor Freeway and Arroyo Seco Parkway). In 2006, the interchange was officially renamed in the memory of Los Angeles traffic and weather reporter Bill Keene.
Description
The highway is a stack interchange that connects U.S. Route 101 to State Route 110. All movements are possible in this interchange between US 101, which crosses over SR 110, but not necessarily with surrounding roads, like Sunset Boulevard, which crosses SR 110 just northeast of the interchange. The interchange is located at Exit 3 of US 101 and Exit 24A of SR 110.
The four freeway segments ("paths" of travel) from the Four Level Interchange are:
US 101 north (Hollywood Freeway) – Ventura
US 101 south (Santa Ana Freeway) to I-5 south / I-10 east / SR 60 east
SR 110 north (Arroyo Seco Parkway) – Pasadena
SR 110 south (Harbor Freeway) to I-110 south – San Pedro
History
While the highway oriented east–west at this intersection has consistently been numbered US 101, the numerical designation of the road oriented north–south at this interchange has changed over the years. Originally designated U.S. Route 66 and U.S. Route 6 and later signed as State Route 11, all of these designations were eventually removed from the intersection and replaced with the current designation of Route 110.
The four-level reinforced concrete structure was designed by a team of engineers and built by the James I. Barnes Construction Company. Although it was finished in 1949, it was not put into full use until the freeways it served were completed and opened on 22 September 1953.
Begin with the source’s own compact description: “Four Level Interchange” is interchange in Los Angeles County, California, United States. The dossier treats that line as a proposition to test through Four, Level and Interchange, not as a finished interpretation.
Why this record matters
The phrase “interchange in Los Angeles County, California, United States” supplies a clear boundary for inquiry. It also exposes the unanswered questions: who defined that boundary, when it became stable and which sources sit outside it.
The strongest evidence will usually combine a dated visual record with documents produced by the authority responsible for the place. The source revision retrieved here is dated Sep 4, 2026. The linked authority identifier is Q805998. Authority coordinates are 34.063, -118.249. 1 of 1 selected statements include explicit references; 0 carry qualifiers and 0 use preferred rank. The first chronological checks are 1949, 1953 and 2006.
Architectural summaries often privilege surviving fabric and can understate demolished phases, contested use or displaced communities. The source lead contains qualifying language; that uncertainty should survive quotation, summary and reuse. 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 “Four Level Interchange”, its source revision and the description used here.
- Expand the search: follow Four Level Interchange primary sources, Four Level Interchange archive and Four 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 “Four Level Interchange”?
- What physical evidence or contemporary plan supports the description?
- Which authority defined the place, boundary or structure at the relevant date?
Search terms from this dossier
This entry incorporates text from “Four Level Interchange” 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.