Source: December 31, 2018 Interstate Route Log and Finders List
I-110 California Annual Average Daily Traffic
Downtown Los Angeles
Source: Caltrans, Traffic Operations Program - Traffic and Vehicle Data Systems 
Los Angeles Vicinity - 1966 California Official Highway Map
California 11 was replaced by Interstate 110 while California 7 became Interstate 710. SR 7 was reused for a new border crossing linking I-8 with Mexicali in Imperial County. SR 11 is designated along a freeway between SR 905 and the Mexican border at Otay Mesa, San Diego.
Interstate 110 is the Harbor Freeway connecting San Pedro (a community of Los Angeles) near the Ports of Los Angeles and Long Beach with Downtown Los Angeles. It is an Interstate highway between its junction with California 47 near San Pedro north to Interstate 10/Santa Monica Freweay near Downtown Los Angeles. A heavily traveled route, Interstate 110 serves as a major commuter route through the heart of South Los Angeles as well as a commercial corridor connecting the Port of Los Angeles with transcontinental Interstate 10 and Interstate 5/Golden State Freeway.
The Harbor Freeway is one of several major north-south freeways in the Southland. Interstate 110 is sandwiched mostly within or adjacent to the narrow strip of the city of Los Angeles that extends southward from near downtown toward San Pedro and the Pacific Ocean from the Central Business District. This strip of land allows the city of Los Angeles to connect by land to the valuable port properties, including San Pedro.
Between 1964 and 1968, Interstate 110 was commissioned as an Interstate linking Interstate 5/10 and U.S. 101 north of Downtown Los Angeles, as shown in the map below. Interstate 110 ended at the same interchange where former Interstate 105 ended. In 1968, Interstate 110 was decommissioned, and the stub freeway was folded into unsigned California 10. AASHTO approved the deletion of both I-105 and I-110 on June 30, 1970.
The short lived segments of Interstates 105 and 110 by Downtown Los Angeles in 1966.
Interstate 110 was resurrected in 1978 along a different stretch of highway: the Harbor Freeway, California 11. The Harbor Freeway is one of the oldest freeways in the Los Angeles Basin, having been built in stages through the 1950s and 1960s. The first sections were constructed as part of U.S. 6 and California 11, which previously followed Figueroa Street from Downtown Los Angeles to San Pedro.
When U.S. 6 was decommissioned in 1964, the Harbor Freeway was redesignated as California 11. Between 1964 and 1981, the Harbor Freeway, along with the adjacent Pasadena Freeway to the north, was marked as California 11. California 11 was accepted into the Interstate Highway System in 1978, and the route was renumbered in 1981 as Interstate 110 (and California 110 for the non-Interstate standard sections) to conform to Interstate route number standards. AASHTO approved the I-110 designation from SR 47 to I-10 on June 25, 1979.
While Interstate 110 carried the freeway from San Pedro to Interstate 10 near Downtown, California 110 lines the route northeasterly through Downtown toward Pasadena and Glenarm Street along one former alignment of U.S. 66. The section of the SR 110 freeway northeast of Interstate 5 is known as the Pasadena Freeway, but it was originally known as the Arroyo Seco Parkway, which was built in the 1940s and 1950s. This stretch of freeway is not up to Interstate standards, especially north of Interstate 5. Many of the original sub-standard sections of the Arroyo Seco Parkway remain, including short acceleration and deceleration lanes, stop signs at the freeway entrance, minimal shoulders, the Figueroa Tunnels, sharp turns, and narrow lanes. Due to its historical status, many of these features will be not be modified.
Prior to 2000, two state route California 110 segments existed: one at the northern end of the Interstate and another at the southern end of the Interstate. At the southern end, the southern California 110 followed Gaffey Avenue through San Pedro to reach the cruise ship port. It was reliquished by the state in June 2009. The northern stretch between Glenarm Street and Colorado Boulevard (former U.S. 66) was reliquinshed to the city of Pasadena on August 31, 2000.1
A portion of the freeway just south of Interstate 10 was upgraded with a separate transit and carpool lanes in the center of the freeway, including a brief elevated section over the portion of the Harbor Freeway that lies below grade. The elevated portion ends prematurely by the West 28th Street overpass.
Southern Terminus - California 47 and Gaffney Street - Los Angeles (San Pedro), California
Perspective from Interstate 110 (Harbor Freeway) south
Southbound Interstate 110 3/4-mile before southern terminus approaching California 47. Photo taken by Andy Field/Casey Cooper/Joel Windmiller/Mark Furqueron (7/21/01).
Southbound Interstate 110 1/2-mile before southern terminus at California 47. Photo taken by Andy Field/Casey Cooper/Joel Windmiller/Mark Furqueron (7/21/01).
Continuing south, Interstate 110/Harbor Freeway approaches its terminus at the point where it empties into Gaffney Street in San Pedro. Photo taken by Andy Field/Casey Cooper/Joel Windmiller/Mark Furqueron (7/21/01).
The transition from Interstate 110/Harbor Freeway south onto Gaffney Street occurs quickly after the California 47/Seaside Freeway (Vincent Thomas Bridge) interchange. Photo taken by Andy Field/Casey Cooper/Joel Windmiller/Mark Furqueron (7/21/01).
This stoplight marks the southern end of Interstate 110. During the 1990s, California 110 resumed south of this point along Gaffey Street. Now the Interstate and State Route terminate here, at its junction with California 47. The Interstate shield in the overhead sign is erroneous, as the Interstate ends here. Photo taken by Andy Field/Casey Cooper/Joel Windmiller/Mark Furqueron (7/21/01).
Perspective from California 110 (Gaffney Street) north
Northbound Gaffney Street approaching beginning of both Interstate 110 and California 47 in San Pedro (a community of Los Angeles). Photo taken by Andy Field/Casey Cooper/Joel Windmiller/Mark Furqueron (7/21/01).
Interstate 110 begins at the point where Gaffney Street (hidden California 110) feeds Interstate 110 in San Pedro. Photo taken by Andy Field/Casey Cooper/Joel Windmiller/Mark Furqueron (7/21/01).
Perspective from Interstate 110 (Harbor Freeway) north
Northbound Interstate 110 at California 47 split, just beyond Interstate 110 southern terminus. Photo taken by Andy Field/Casey Cooper/Joel Windmiller/Mark Furqueron (7/21/01).
Northern Terminus - Interstate 10 - Los Angeles, California
Perspective from Interstate 110 (Harbor Freeway) north
The first appearance of the junction with Interstate 10 on northbound Interstate 110/Harbor Freeway is on this mileage sign prior to Exit 20B, Exposition Boulevard. Exposition Boulevard runs close to the University of Southern California, one of the most prestigious private schools in California. The next exits are for Exit 20C, Adams Boulevard and Exit 21, Interstate 10/Santa Monica Freeway east to San Bernardino and west to Santa Monica. Photo taken 09/25/05.
The transitway lanes, which have been following Interstate 110/Harbor Freeway north for several miles, will come to an end before Interstate 110 reaches Interstate 10 and downtown Los Angeles. The white guide signs provide the connections afforded via the transitway exits. Northbound Interstate 110/Harbor Freeway reaches Exit 20B, Exposition Boulevard and 37th Street. The next exit along northbound is Exit 20C, Adams Boulevard. Photo taken 09/25/05.
Immediately thereafter, the Interstate 110/Harbor Freeway transitway and high occupancy vehicle lanes completely separate from the freeway to provide direct access to multimodal terminals and parking areas in downtown Los Angeles. This mileage sign provides the distance to Exit 20C, Adams Boulevard; Exit 21, Interstate 10; and Exits 22-23A, Downtown Los Angeles exits to 9th Street and 6th Street via collector distributor lanes. Photo taken 09/25/05.
Northbound Interstate 110/Harbor Freeway reaches Exit 20C, Adams Boulevard exit just as the transitway crosses over the freeway. The next interchange is with Exit 21, Interstate 10/Santa Monica Freeway. Photo taken 09/25/05.
The transitway leaves the freeway after the Adams Boulevard off-ramp. The right two lanes become exit only for Interstate 10/Santa Monica Freeway. Photo taken 09/25/05.
This mileage sign provides the distance to Exit 21, Interstate 10; Exits 22-23A, Downtown Los Angeles (9th Street and 6th Street); and Exits 23B-C, 4th Street and 3rd Street. The best views of downtown Los Angeles and its famous skyline may be seen from Interstate 110/Harbor Freeway as it approaches Interstate 10/Santa Monica Freeway. Rising above the basin, the towers of downtown Los Angeles cluster together in a relatively small area bounded by the Interstate 10, California 110, U.S. 101, and Interstate 5 freeways. Photo taken 09/25/05.
The next advance sign is the first to advise that Interstate 110 is transitioning onto California 110. The Interstate highway ends at Interstate 10, and the state route freeway continues from there northeast to Pasadena. Between 1998 and 2003, not much has changed at this sign bridge, except that the pull-through sign for northbound California 110 now reads LEFT 3 LANES at the bottom. This is the first sign that shows that through traffic will be defaulted onto California 110 rather than Interstate 110. Based on photos we have taken between those years, it appears that Toyota has used the billboard to the east of the freeway for its ads for at least five years. Photo taken 09/25/05.
These tiny reflective signs for the upcoming Interstate 10/Santa Monica Freeway interchange are pasted onto the overpass. Due to their size, they are barely visible to northbound Interstate 110 drivers as they struggle to line up in the correct lane. During commuting hours, Interstate 110 is frequently delayed, including the area around this interchange. Photo taken 09/25/05.
Northbound Interstate 110/Harbor Freeway reaches Exit 21, Interstate 10/Santa Monica Freeway. Interstate 10 is very close to its own terminus: it begins just a few miles west of here in Santa Monica. However, its eastern terminus is several thousand miles east of here, in Jacksonville, Florida. Known as the Christopher Columbus Transcontinental Highway, Interstate 10 is one of the nation's busiest highways near the Interstate 110 interchange. The Santa Monica Freeway/Interstate 10 near downtown routinely battles the Dan Ryan Expressway (Interstate 90/94) in Chicago for the title of busiest freeway. The impact of the Northridge Earthquake of 1994 was tremendous, as portions of the Santa Monica Freeway/Interstate 10 collapsed near here. Photo taken 09/25/05.
View of the signage above the transition ramp from northbound Interstate 110 to Interstate 10. This marks the northern terminus of Interstate 110, but the freeway continues as California 110 into downtown Los Angeles. There are no end shield assemblies or signs present. Photo taken 09/25/05.
Perspective from California 110 (Harbor Freeway) north
Use the left three lanes to continue north on California 110/Harbor Freeway into downtown Los Angeles. The exit numbers continue to follow Interstate 110. The first exit on the state route freeway is Exits 22-23A, 9th Street and 6th Street (to Downtown Los Angeles). Watch for stopped traffic on this section of California 110... it frequently backs up. Photo taken 09/25/05.
Perspective from Interstate 10 (Santa Monica Freeway) west
Westbound Interstate 10 (Santa Monica Freeway) reaches Exit 14A for Los Angeles Street and the LA Convention Center. The ensuing ramp connects I-10 with I-110 (Harbor Freeway) south and California 110 north. Photo taken 03/24/16.
All traffic for I-110 south to San Pedro and California 110 north to Downtown Los Angeles and Pasadena departs in unison from I-10 west at Exit 13. Interstate 110 serves interests to the University of Southern California and the LA Coliseum. The Harbor Freeway Transitway is also available for high occupancy vehicles along southbound I-110. Photo taken 03/24/16.
Historic Perspective from Interstate 10 west
The first indication of the approaching Interstate 110 and California 110 interchange (Exit 13) is this interchange sequence sign posted along Interstate 10 west. Photo taken 08/24/04.
This set of button copy signs was carbon copied with fully reflective signs by 2008. A gore sign for Exit 14A was added, but the panel for I-110/SR 110 remained unnumbered. Photo taken 08/24/04.
Both Interstate 110 and California 110 are the Harbor Freeway as far north as the Four Level Interchange with U.S. 101. The Harbor Freeway directly transitions into the Pasadena Freeway (old Arroyo Seco Parkway) northeast of the Four Level Interchange. While there are signs on southbound U.S. 101 that seem to state that California 110 between I-10 and U.S. 101 is apart of I-110, signs along the Santa Monica Freeway indicate otherwise. Photo taken 08/24/04.
Shields for Interstate 110 and SR 110 covered up original signage that showed California 11 shields, and in some cases, even a U.S. 6 shield. U.S. 6 used to follow the Harbor Freeway from the Golden State Freeway (U.S. 99, now Interstate 5) south to the Pacific Coast Highway (Alternate U.S. 101, now California 1). Signs for U.S. 6 were removed from the Harbor Freeway in 1964, the same year in which U.S. 6 was decommissioned south of Bishop. California 11 was signed on the Harbor Freeway until 1981, when it became I-110 and SR 110. I-710 was not created until 1984, so there was a three-year gap between the creation of the two Interstate routes. Photo taken 08/24/04.
Much of this stretch of Interstate 10 is on an elevated viaduct, parts of which were damaged during the 1994 Northridge Earthquake. Retrofitting projects resulted in viaducts and bridges that can withstand stronger earthquakes without collapsing. Photo taken 08/24/04.
This set of button copy signs was replaced by 2008 to display the same information. Exit numbers were not added for the Harbor Freeway ramps. Photo taken 08/24/04.
Perspective from Interstate 10 (Santa Monica Freeway) east
Now traveling east on Interstate 10/Santa Monica Freeway, Exit 13A, Interstate 110/Harbor Freeway south is a right exit, while the connection to Exit 13B, California 110/Harbor Freeway north is a left exit. Photo taken 04/21/07.
Eastbound Interstate 10/Santa Monica Freeway reaches Exit 13B, California 110/Harbor Freeway north to downtown Los Angeles and Pasadena. Photo taken 04/21/07.
Perspective from Interstate 110 (Harbor Freeway) south
This sign along southbound California 110 at its interchange with Interstate 10/Santa Monica Freeway is one of the first overhead signs to show Interstate 110. At this point, the Harbor Freeway continues its southerly journey toward San Pedro as an Interstate highway. Photo taken by Mike Ballard (6/7/99).
Alternate Northern Terminus - U.S. 101 - Los Angeles, California
Perspective from California 110 (Harbor Freeway) north
Traveling through downtown Los Angeles, the first advance signage on northbound California 110/Harbor Freeway for the Four-Level Interchange with U.S. 101/Santa Ana and Hollywood Freeways is this overhead sign. Photo taken 04/21/07.
The right two lanes become exit only for U.S. 101 north to Hollywood and Ventura and U.S. 101 south to Interstate 5 south to Santa Ana and Interstate 10 east to San Bernardino. The left three lanes continue north on California 110 to Pasadena and to Interstate 5 north. Photo taken 04/21/07.
After this interchange, no trucks over three tons are permitted on northbound California 110/Pasadena Freeway (Arroyo Seco Parkway). Trucks may use either direction of U.S. 101, however. If Interstate 110 extends this far north (based on signage on U.S. 101), the Four-Level Interchange is as far as the Interstate designation goes due to the truck restriction. (Note that some Interstate highways, such as Interstate 580 in Oakland, have truck restrictions.) Photo taken 04/21/07.
Northbound California 110/Harbor Freeway meets U.S. 101 at the Four-Level Interchange. To the southeast, U.S. 101 follows the Santa Ana Freeway to the East Los Angeles Interchange with Interstate 5/Golden State Freeway and Interstate 10 (San Bernardino and Santa Monica Freeways). To the northwest, U.S. 101/Hollywood Freeway aims toward the Cahuenga Pass, then splits at the Ventura Freeway near Universal City. To the northeast, California 110 follows historic Arroyo Seco Parkway (former U.S. 66) to Pasadena. Photo taken 04/21/07.
Entering the Four-Level Interchange from northbound California 110, the left lanes connect to U.S. 101/Hollywood Freeway north, while the right lanes connect to U.S. 101/Santa Ana Freeway south to Interstate 5 and Interstate 10. Photo taken 04/21/07.
The massive Four-Level Interchange rises from the transition ramp that connects California 110 north with U.S. 101/Hollywood Freeway north. Photo taken 04/21/07.
Perspective from U.S. 101 (Santa Ana Freeway) north
The first advance signage on northbound U.S. 101/Santa Ana Freeway for the junction with California 110 is this older sign. Use California 110 north to Pasadena and south to San Pedro and the Port of Los Angeles. The interchange between U.S. 101 and California 110 is the Four-Level Interchange, one of the first symmetrical stack interchanges of its design to be built in the state. The Santa Ana Freeway (along with the other three named freeways that enter the stack interchange) ends at the Four-Level Interchange. Photo taken 07/01/07.
A newer reflective sign shows California 110/Pasadena Freeway (Arroyo Seco Parkway) north to Pasadena and Interstaet 110/Harbor Freeway south to San Pedro. Through traffic follows U.S. 101/Hollywood Freeway north to Ventura. Photo taken 07/01/07.
Northbound U.S. 101/Santa Ana Freeway reaches Exit 3, California 110 north and Interstate 110 south. From here, U.S. 101 follows the Hollywood Freeway north to Hollywood and to Ventura. Photo taken 07/01/07.
Perspective from U.S. 101 (Hollywood Freeway) south
Recently (2004), signs were erected on southbound U.S. 101 (Hollywood Freeway) that seem to indicate that Interstate 110 begins at the Four-Level Interchange just north of downtown Los Angeles. The Four Level Interchange is well known locally; it is the convergence point between the Santa Ana Freeway (U.S. 101 from the southeast), Hollywood Freeway (U.S. 101 from the northwest), Pasadena Freeway (California 110 from the northeast), and Harbor Freeway (California 110 from the southwest). The advance signs for the Four Level Interchange (Exit 3B for southbound U.S. 101 traffic) indicate that it is the northern end of Interstate 110, and California 110 continues northeast from here. Photo taken 08/24/04.
The next sign bridge refers to the pending freeway interchange as simply California 110, but these are older signs than those presented in the previous interchange sequence sign. Although not identified by name on the advance signs, the California 110 Four Level Interchange is steeped in history. A symmetrical stack interchange, the Four Level Interchange is the first of its kind in Southern California. At varying times, old roads such as U.S. 6, U.S. 66, and California 11 used to pass through the Four Level Interchange. Note that the pull through sign already mentions Interstate 5 and Interstate 10, even though the transition ramps to those two routes are still several miles away. Photo taken 08/24/04.
The right two lanes exit onto California 110. With this older sign, both northbound Pasadena Freeway and southbound Harbor Freeway are described as part of California 110. But that does not hold true for the next sign. Photo taken 08/24/04.
Now, Interstate 110 south is clearly signed for the southbound Harbor Freeway, while northbound Pasadena Freeway (which has truck restrictions) is signed as a state route. The October 2002 federal route log lists Interstate 110 as 20.43 miles. The interchange between California 110 and U.S. 101 is Exit 24, which means it is 24 miles north of the southern terminus at California 47 near San Pedro. Unless the southern four miles of Interstate 110 are actually California 110, then the three miles between Interstate 10 (Exit 21) and U.S. 101 (Exit 24) are not an Interstate Highway. Nevertheless, there is ample signage showing California 110 to be Interstate 110 between U.S. 101 and Interstate 10. Photo taken 08/24/04.
Of course, since these signs were put in place after October 2002, it is also possible that the number of Interstate miles for California 110 have increased so as to include California 110 between Interstate 10 and U.S. 101. Aside from common congestion issues, California 110 between Interstate 10 and U.S. 101 appears to be Interstate compatible. The same cannot be said for California 110 northeast of U.S. 101, due to left exits, substandard tunnels, sight distance issues, etc. Here southbound U.S. 101 reaches the transition ramp at Exit 3B to southbound Interstate 110 to San Pedro and northbound California 110 to Pasadena. Photo taken 08/24/04.
Looking at the transition ramp, an older button copy sign has been retrofitted to include an Interstate 110 shield on the overhead, and a trailblazer standalone shield was posted immediately below the sign. Photo taken 08/24/04.