Interstate 710 (I-710 - colloquially referred to as "The Seven-Ten") is a north–south Auxiliary interstate freeway running for 23 miles (37 km) through Los Angeles County, California. Officially known as the Long Beach Freeway, it runs north from Long Beach to Valley Boulevard, just north of I-10, the San Bernardino freeway, near the boundary between cities of Alhambra and Los Angeles. South of I-5, Interstate 710 follows the course of the Los Angeles River, rarely wandering more than a few hundred feet from the riverbed. South of SR 1 in Long Beach, I-710 is officially part of the Seaside Freeway.

Also called the Los Angeles River Freeway prior to November 18, 1954, I-710 was planned at its inception to run all the way north to Pasadena, but the construction of the segment from Alhambra to Pasadena through South Pasadena has been delayed for several decades due to community opposition. Prior to 1983, the road was not an Interstate, although it was built to Interstate standards.[citation needed] Until 1964 it was State Route 15, but it was renumbered to State Route 7 in the 1964 renumbering because of the existence of Interstate 15, and to I-710 in 1983.

This route is part of the California Freeway and Expressway System.

The southern terminus of the freeway presently signed as Interstate 710 is at Ocean Boulevard in Long Beach. From there, the Long Beach Freeway follows the course of the Los Angeles River to Atlantic Boulevard in the city of Bell. 710 then travels roughly due north, east of Downtown Los Angeles, to its current northern terminus at Valley Boulevard (just north of Interstate 10) in Alhambra and the El Sereno neighborhood of Los Angeles.

Near its southern terminus, 710 actually separates into three spur freeways. The first spur carries the Long Beach Freeway designation heading toward Downtown Long Beach and becomes Shoreline Drive after the 6th and 9th Street exits, while the Interstate 710 designation continues on N. Harbor Scenic Drive up to an interchange with Ocean Boulevard. The second spur heads down S. Harbor Scenic Drive after the interchange to the eastern piers of the Port of Long Beach and the Queen Mary. The third spur heads west down Ocean Boulevard, which carries the Interstate 710 designation over Gerald Desmond Bridge onto Terminal Island, where the interstate designation eventually terminates.

There is however a part of 710 in Pasadena that is constructed to freeway standards, extending from California Boulevard north to the Foothill (I-210)/Ventura (Hwy 134) freeway interchange. But the route designation on this freeway stub is unsigned, and is instead marked if it were merely freeway entrance and exit ramps to and from 210.

Legislative Route 167 was defined in 1933 to run from San Pedro east to Long Beach and north to Monterey Park. An extension was added in 1947, taking it north to Pasadena. State Route 15 was signed in 1934 along the section of Legislative Route 167 from Pacific Coast Highway (State Route 3, later U.S. Route 101 Alternate, now State Route 1) in Long Beach north to Garvey Avenue (U.S. Route 99, replaced by Interstate 10) in Monterey Park. The original pre-freeway alignment ran along Los Robles Avenue (Pasadena) and Atlantic Boulevard. The freeway replacement of SR 15/LR 167 was built from 1953 to 1965. The whole route of LR 167, including the proposed extensions west to San Pedro and north to Pasadena, was renumbered State Route 7 in 1964 after it was decommissioned from portions of San Diego Freeway which is now Interstate 405 state highway renumbering, as the number 15 conflicted with Interstate 15. In 1965 the route was truncated to State Route 1 in Long Beach; the part from SR 1 south and west to State Route 47 was deleted, and the rest from SR 47 west to State Route 11 (now Interstate 110) became part of SR 47.

The section of Long Beach Freeway was built from 1954 to 1975. The Long Beach Freeway was approved as a chargeable interstate in September 1983, and the Long Beach Freeway changed out the SR 7 signs with Interstate 710 in 1984. It was added shortly after the Harbor Freeway went up changing out the SR 11 signs with Interstate 110 in 1981. The short stub in Pasadena was built in 1975, along with the adjacent sections of Interstate 210 and State Route 134. To this day, there are still remaining overhead street signs pointing motorists to State Route 7 in Monterey Park.

The section from SR 1 south and west to SR 47 was re-added to the legislative definition at some point. The existing freeway from SR 1 south to Ocean Boulevard was taken over by the state on August 25, 2000 in a trade with the City of Long Beach for former State Route 103 north of SR 1. The rest of the defined route, west on Ocean Boulevard to SR 47, is still locally maintained.

The explosive growth of cargo volumes handled at the ports of Los Angeles and Long Beach has added an enormous amount of truck traffic to the Long Beach Freeway, since it is the most direct route between the port complex and the railyards in Vernon and East Los Angeles, as well as the Pomona and San Bernardino freeways that connect Los Angeles to railyards in San Bernardino and Colton. The freeway's pavement has been badly damaged as a result, since it was not designed to carry nearly as large of a load of truck traffic. It has also become a major source of air pollution, emanating from diesel-fueled trucks idling in rush hour traffic congestion and giving cities along its route some of the worst air quality in already smoggy Southern California. In response, an Environmental Impact Statement/Environmental Impact Report is currently being conducted to analyze possible significant improvements to I-710 between the ports of Long Beach and Los Angeles and the Pomona Freeway (SR-60).

The planned segment from Alhambra to Pasadena through South Pasadena has been subject to legal battles which have stopped construction. Because of these legal disputes, the freeway's northern terminus has been Valley Boulevard since the 1960s. However, a short unsigned freeway does exist in Pasadena, heading south from the interchange of Interstate 210 and State Route 134 to California Boulevard.

As a result of the route's incomplete condition, freeway signs are inconsistent in their identification of the northbound Long Beach Freeway's destination, with some indicating Pasadena as a control city and others identifying Valley Boulevard as the freeway's terminus. For example, approaching I-710 from State Route 60 (Pomona Freeway) in East Los Angeles, westbound traffic is given Valley Boulevard as the destination for northbound I-710, while eastbound traffic is given a destination of Pasadena. Signs at the interchange with Interstate 105 show Pasadena as the destination for northbound I-710.

Currently, traffic headed for Pasadena on I-710 is redirected to Interstate 10 (San Bernardino Freeway) eastbound by signs at the interchange between the two routes in Monterey Park. These signs identify both Pasadena and San Bernardino as control cities for the eastbound San Bernardino Freeway, although it does not actually pass through Pasadena. Rather, traffic to the city is directed to take State Route 19 (Rosemead Boulevard) northbound from its junction with I-10 (about 6 miles (9.7 km) east of the Long Beach Freeway) to reach Pasadena. Traffic from northbound I-710 is routed onto Fremont Avenue in Alhambra and South Pasadena, and the Pasadena Freeway (State Route 110).

The areas around I-710, northeastern Los Angeles and the northwestern San Gabriel Valley are subject to traffic congestion. There are no completed north–south freeways in the twelve-mile area between Interstate 5 (Golden State Freeway) and Interstate 605 (San Gabriel River Freeway). Pro- and anti-710 lobbies have debated whether finishing I-710 would alleviate any of the San Gabriel Valley's traffic congestion, or merely displace it from surface streets to the freeway.

Caltrans and its local partner, the Los Angeles County Metropolitan Transportation Authority (Metro), are researching the possibility of extending the Long Beach Freeway from Valley Boulevard to Pasadena by building a tunnel under Alhambra, El Sereno, and South Pasadena. The premise is that a tunnel would allow Caltrans to extend the freeway without disturbing the residential neighborhoods on the surface, similar to other tunnels throughout the world. The proposed twin 4.5-mile-long tunnels would be the longest in the United States, but are small compared with others around the world. Between January and May 2009, Caltrans conducted soil samples for the tunneling project in the Pasadena area and is currently in the process of completing a combined environmental impact statement (EIS) and environmental impact report (EIR), in which the tunnel is one option.

In August 2012, Metro narrowed down the list of potential alternatives to study in the EIR/EIS process. The alternatives include: (1) a no-build alternative, where no additional infrastructure would be built to address the gap in the freeway plan between Valley Blvd and I-210; (2) a roadway tunnel without exits to connect the northern terminus of the freeway at Valley Blvd to Pasadena; (3) a light rail line connecting East L.A. with Pasadena using a route that travels along the I-710 right of way until Valley Blvd where it would become a subway until connecting with the Metro Gold Line at the Filmore Metro station in Pasadena; (4) a bus rapid transit line from Montebello to Pasadena; and (5) Transportation System Management/Transportation Demand Management (TSM/TDM).

Except where prefixed with a letter, postmiles were measured on the road as it was in 1964, and do not necessarily reflect current mileage. The entire route is in Los Angeles County.

The entire route is in Long Beach, Los Angeles County.

The entire route is in Long Beach, Los Angeles County.