TheBlue Line (officially theUC San Diego Blue Line for sponsorship purposes) is a 26.3-mile (42.3 km)[5][6]light rail line in theSan Diego Trolley system, operated by San Diego Trolley, Inc., an operating division of theSan Diego Metropolitan Transit System (MTS).[5] With an end-to-end travel time of one hour and twenty-three minutes, it operates betweenUTC Transit Center andSan Ysidro Transit Center, the latter of which is at theMexico–United States border directly adjacent to theSan Ysidro Port of Entry, facilitating easy connections across the border.[7] The line servesLa Jolla,downtown San Diego,National City,Chula Vista, andSan Ysidro[8] and is the system's longest line.
The Blue Line is one of five lines in the trolley system, along with theOrange,Green,Copper, andSilver ("heritage weekend" service only) lines.[5] Among them, the Blue Line has the highest ridership, transporting 24,389,986 total riders, or 75,160 per day, infiscal year 2024.[3] Its sponsored name is due to a $30 million naming rights deal withUC San Diego Health.[9] An extension to its namesake campus of theUniversity of California, San Diego, as well as nine other stations, opened to revenue service on November 21, 2021.[10][11]
The initial line in the San Diego Trolley system, the Blue Line first opened between Centre City San Diego and San Ysidro on July 26, 1981,[4][12] at a cost of $86 million (equivalent to $297 million in 2024), using the existing tracks of theSan Diego and Arizona Eastern Railway, which the Metropolitan Transit Development Board had purchased fromSouthern Pacific on August 20, 1979, for $18.1 million (equivalent to $78 million in 2024).[13]
In 1986, the line was named theSouth Line to differentiate it from the newEast Line toEuclid Avenue, which later became theOrange Line. On July 2, 1992, the line was extended north from downtown with the opening ofCounty Center/Little Italy station.[12] It was renamed the North-South Line when the Old Town extension opened on June 16, 1996.[12] The North-South Line was renamed theBlue Line in 1997,[4] with the opening of the extension to Mission San Diego on November 23, 1997.[12]
When the Green Line was brought into service in 2005, the Blue Line was cut back toOld Town Transit Center. At rush hours, however, some Blue Line trains continued onto Qualcomm Stadium; and from Qualcomm Stadium onto San Ysidro. On September 3, 2006, the rush hour service Blue line trains were discontinued entirely, due to duplication of service withGreen Line service. All Blue Line trains then terminated at Old Town. Rush hour Blue Line trains operated from San Ysidro to America Plaza with some serving the Bayside.
Blue Line service also experienced some change in the stations served. The San Diego Square station located between 7th and 8th Avenues in downtown closed in 1986 due to low ridership and its close proximity to Fifth Avenue station. Later that year,E Street station in Chula Vista opened in October 1986,[12] about five years after service already operated along the tracks served. At the same time, the Centre City station on C Street, between Sixth Avenue and Fifth Avenue, was renamedFifth Avenue station.Fenton Parkway station was an 'infill' station that opened in 2000; however, it, like the rest of the stations on the route to Mission San Diego, is now only served by theGreen Line.
During a system redesign which took effect on September 2, 2012, Blue Line service between America Plaza and Old Town was discontinued, makingAmerica Plaza the Blue Line's northern terminus.[14] Blue Line trains traveled between America Plaza to San Ysidro on a regular 15 minute frequency, with a7+1⁄2 minute frequency during weekday rush hours.[14][15] Blue Line service to Old Town was reinstated once the Mid-Coast trolley extension to UC San Diego was completed.[16] UC San Diego Health paid $30 million to rename the route theUC San Diego Blue Line in 2015.[17]
To accommodate the newSiemens S70 models and allow for their use on the line, the Blue Line stations needed to undergo renovation, although this was done over a period of five years to prevent the disruption of operation of the trolley.[18] The project to renovate the stations, called the Trolley Renewal Project, began in fall 2010.[19][20] After beginning operation on the Green Line in 2011 and on the Orange Line in 2013,low-floor Siemens S70 LRVs began operation on the Blue Line on January 27, 2015.[21] Renovation of rail track and the final eleven Blue Line stations was completed in late 2015.[22][23]
TheMid-Coast Corridor Transit Project was an 10.9-mile (17.5 km)[6] extension of the Blue Line from the Old Town Transit Center north toLa Jolla Village,University of California, San Diego, andUniversity City.[24][25] Ridership is projected at 34,700 trips in 2030.[26] The extension primarily follows the right-of-way of theCoaster andInterstate 5, with an elevated deviation around the UCSD area. MTS estimated construction costs of $2.1 billion.[26] An aim of the extension is to decrease demand for parking on the UCSD campus while providing direct trolley access toWestfield UTC, a popular shopping mall. The existingSuperLoop BRT Shuttle (Routes 201/202) provides transit in and around the UTC area from the nearby trolley stations.[27] Testing of the line began in June 2021,[28] and it opened to revenue service on November 21, 2021,[11] although alternate weekday and weekend late night Blue Line trips still short turn at America Plaza.[29][30]
The Mid-Coast Corridor Transit Project was done in conjunction with theNorth Coast Corridor project, which upgrades theLOSSAN Corridor further to the north. Both projects build upon the original right-of-way of theSurf Line, which was built in the 1880s as the original railway from Los Angeles to San Diego.
On January 26, 2025, the MTS establishedbus route 910, an "OvernightExpress" bus operating on the southern section of theBlue Line from midnight to 5 A.M., when the Blue Line isn't running.[31] Route 910 operates betweenSanta Fe Depot andSan Ysidro Transit Center, with intermediate stops at theCity College,12th & Imperial,24th Street,Palomar Street, andIris Avenue transit centers.[32]
| Station | Location | Connections[33] |
|---|---|---|
| UTC | University City, San Diego | |
| Executive Drive |  MTS:Rapid 204,Rapid 237,921A,979 | |
| UC San Diego Health La Jolla |
| |
| UC San Diego Central Campus | La Jolla, San Diego |
|
| VA Medical Center | ||
| Nobel Drive | ||
| Balboa Avenue | Bay Park, San Diego | |
| Clairemont Drive | MTS:105 | |
| Tecolote Road | Morena, San Diego |  Park and ride: 279 spaces |
| Old Town | Old Town, San Diego |
|
| Washington Street | Mission Hills, San Diego |
|
| Middletown | Middletown, San Diego |
|
| County Center/Little Italy | Little Italy, San Diego |  Green Line |
| Santa Fe Depot[a] | Core, San Diego | |
| America Plaza[b] | ||
| Civic Center |  Orange Line Silver Line | |
| Fifth Avenue |
| |
| City College | East Village, San Diego | |
| Park & Market |
| |
| 12th & Imperial[c] |
| |
| Barrio Logan[d] | Logan Heights, San Diego | |
| Harborside | ||
| Pacific Fleet | Naval Base San Diego | |
| 8th Street | National City | |
| 24th Street | ||
| E Street | Chula Vista |
|
| H Street | ||
| Palomar Street | ||
| Palm Avenue | Palm City, San Diego | |
| Iris Avenue | Otay Mesa West, San Diego | |
| Beyer Blvd. | San Ysidro, San Diego | |
| San Ysidro | MTS:906,907 |
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Although the current Blue Line ends atSan Ysidro Transit Center, just north of theMexico–United States border, future plans for the Blue Line to continue into Tijuana are awaiting approval. If it is to be made, the Blue Line would be extended 1 or 1.5 miles (1.6 or 2.4 km)[38][39] onelevated trackage[40] into a new Tijuana station.[41] This proposal for a "Cross-Border Trolley", supported bySANDAG[42] and officials in Baja California,[43] could take eight years to complete.[44]
Trolley Route 510 (UC San Diego Blue Line): San Ysidro to University City
LRT 510 Blue Line (San Ysidro to UTC)
Service frequency north of America Plaza will be every 15 minutes, seven days/week, with a span of service similar to current. Frequency south of America Plaza will remain at every 7.5 minutes on weekdays.
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