History of Interstate 15 in California

By | October 14, 2022

Interstate 15 replaced US 395 between San Diego and Temecula, and US 66 between San Bernardino and Barstow. North of Barstow, the highway replaced US 91. The highway was initially planned from I-10 in San Bernardino to Nevada, but the state of California wanted the highway to start in San Diego, which proved successful. The old I-15 between San Bernardino and Devore became I-215.

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San Diego

Already in 1951 the first part was opened in San Diego. For a long time, however, this was the only part in the San Diego area, partly because the suburbs north of San Diego only developed later, as most of the growth took place in nearby Los Angeles. In the late 1970s, construction was mainly done north of San Diego, in the Escondido region. Most of the remaining parts were constructed in the 1980s, and most of them were completed in 1985. Except for one short piece in San Diego, which is the stretch of road between I-805 and I-8. This section was missing for a long time, and traffic had to detour via I-805 and I-8. Not a big detour, but it did cause unnecessary traffic on these highways. This missing link was not opened to traffic until 2000.

Express lanes

Until 2012, the I-15 between SR-163 in San Diego and SR-78 in Escondido has been drastically widened, a separate toll road with 2×2 lanes has been built in the central reservation. Since then, the highway has 14 lanes here.

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Opening history

This is the opening history in the San Diego area.

From Unpleasant Length Opening
Ocean View Blvd SR-94 Martin Luther King Fwy 2 km 00-00-1951
SR-94 Martin Luther King Fwy I-805 2 km 16-07-1970
SR-78 Packard Fwy Center City Pkwy 4 km 28-02-1977
Via Rancho Parkway SR-78 Packard Fwy 8 km 18-03-1977
Miramar Road Poway Road 6 km 19-04-1978
I-5 Ocean View Blvd 1 km 05-05-1978
Center City Drive Deer Springs Road 4 km 04-10-1979
Gopher Canyon Road Lilac Road 5 km 13-05-1980
Deer Springs Road Gopher Canyon Road 7 km 07-08-1980
Camino del Norte Via Rancho Parkway 8 km 28-01-1981
Lilac Road Palo Mesa Drive 4 km 14-04-1981
San Diego Mission Road Aero Drive 3 km 22-05-1981
Aero Drive Tierra Santa Blvd 1 km 06-05-1982
Poway Road Camino del Norte 7 km 28-07-1982
SR-163 Cabrillo Fwy Miramar Road 4 km 28-10-1982
Palo Mesa Drive Mission Road 6 km 06-02-1983
I-8 San Diego Mission Road 1 km 28-10-1984
Mission Road Riverside County Line 7 km 24-02-1985
Tierra Santa Blvd SR-163 Cabrillo Fwy 4 km 07-05-1985
I-805 I-8 5 km 18-01-2000

Los Angeles / Inland Empire

From the San Diego state line, I-15 was gradually extended north to Lake Elsinore between 1973 and 1982. At the same time, sections northwards between Lake Elsinore and Corona were also opened in 1975. Thereafter, there was a fairly long hiatus between Corona and Ontario, which opened only in 1989, one of the last completions of a mainline Interstate in the state of California. In the mid to late 1970s, I-15 opened up around Ontario, Rancho Cucamonga, and west of San Bernardino. The oldest part dates from 1969 and includes the part from San Bernardino to the Cajon Pass.

Devore Interchange

Between 2013 and 2016, the interchange between I-15 and I-215, the ‘Devore Interchange’ north of San Bernardino, was reconstructed. Originally this was a simple interchange with direct connecting roads, where freight traffic on I-15 in particular had to shift a number of lanes to the left to follow the highway. To tackle this problem, truck bypass routes have been constructed with separate lanes for freight traffic around the interchange, so that there are fewer lane changes and weaving movements. The project cost $324 million and was completed on May 20, 2016, 18 months ahead of schedule.

Express lanes

Between 2018 and 2021, express lanes were built on I-15 between Cajalco Road in southern Corona and SR-60 in Jurupa Valley. This project involved 25 kilometers of toll lanes built in the median strip of the existing motorway. Unlike some projects in which HOV lanes have been converted into toll lanes, this was a capacity expansion. The $472 million project began in April 2018 and the express lanes opened on April 10, 2021. The project is also known as Riverside Express.

Opening history

This is the opening history in the Corona region.

From Unpleasant Length Opening
San Diego County Line Temecula Pkwy 5 km 23-03-1973
El Cerrito Road Magnolia Avenue 4 km 01-12-1975
Temescal Canyon Road El Cerrito Road 7 km 30-12-1975
Temecula Pkwy Winchester Road 5 km 30-09-1976
Winchester Road Los Alamos Road 5 km 23-12-1977
Los Alamos Road Clinton Keith Road 6 km 26-09-1978
Indian Truck Trail Temescal Canyon Road 6 km 26-09-1979
Lake Street Indian Truck Trail 6 km 28-05-1980
Central Avenue Lake Street 6 km 07-11-1980
Clinton Keith Road Olive Street 6 km 04-09-1981
Olive Street Central Avenue 8 km 08-07-1982
Magnolia Avenue SR-91 Riverside Fwy 2 km 21-04-1987
SR-91 Riverside Fwy SR-60 Pomona Fwy 16 km 28-02-1989
Opening history

This is the opening history in the Ontario & San Bernardino region.

From Unpleasant Length Opening
Glen Helen Pkwy Cajon Pass 14 km 07-11-1969
I-10 4th St 1 km 14-04-1975
4th St Foothill Blvd 4 km 30-10-1975
Sierra Avenue Glen Helen Pkwy 3 km 24-12-1975
Foothill Blvd Sierra Avenue 12 km 22-09-1976
Jurupa St I-10 2 km 02-02-1978
SR-60 Pomona Fwy Jurupa St 2 km 23-03-1979

Mojave Desert

The section through the Mojave Desert is the oldest of I-15 in California. Between 1958 and 1965, the highway was opened between Barstow and the Nevada state line. In 1972 the last section south of Barstow opened to traffic.

Interstate 15 is undergoing a major upgrade project between Devore and the Nevada border. This highway is very busy as it connects the cities of Los Angeles, San Diego and Las Vegas. Most of this route consisted of 2×2 lanes. The project began in 2002 at a cost of $349 million and involved repaving the entire route and adding 63 kilometers of climbing lanes for trucks. In many places freight traffic drives over the widened hard shoulder. Service areas have also been improved and exit numbers have been added. California did not have exit numbers until recently, but only adds them when maintenance needs to be carried out to reduce costs.

In 2022, an 8-kilometer-long rush- hour lane on I-15 near the Nevada border will be completed.

Opening history

I-15 at Temecula.

From Unpleasant Length Opening
National Trails Highway Pacific Rail underpass 9 km 00-00-1958
Hodge Road L Street 18 km 00-00-1958
L Street Ghost Town Road 16 km 00-00-1961
East Baker Blvd Cima Road 39 km 00-00-1961
Cima Road Nevada State Line 38 km 00-00-1963
Ghost Town Road Field Road 36 km 09-06-1964
Field Road Basin Road 26 km 19-10-1964
Oak Hill Road US 395 5 km 12-01-1965
Basin Road East Baker Blvd 29 km 07-10-1965
US 395 Palmdale Road 14 km 03-01-1966
roadway split Oak Hill Road 7 km 10-08-1966
Cajon Pass roadway split 3 km 03-08-1970
Palmdale Road National Trails Highway 5 km 04-08-1971
Pacific Rail underpass Hodge Road 17 km 22-12-1972


Cajon Pass

Construction of express lanes over Cajon Pass north of San Bernardino is being considered. Due to the rapid growth of the High Desert region, traffic to the rest of the Inland Empire and Los Angeles is increasing. Two toll lanes in each direction are assumed.

Traffic intensities

The express lanes north of San Diego.

Exit Place 2007 2012 2016
Exit 1 San Diego ( I-5 ) 106,000 107,000 108,000
Exit 3 San Diego ( I-805 ) 159,000 159,000 173,000
exit 6 San Diego ( I-8 ) 213,000 197,000 217,000
exit 12 San Diego ( SR-163 ) 302,000 293,000 305,000
Exit 19 San Diego ( SR-56 ) 236,000 223,000 234,000
exit 32 Escondido ( SR-78 ) 132,000 128,000 150,000
exit 63 Temecula ( I-215 ) 195,000 180,000 198,000
Exit 64 Murrieta 116,000 106,000 114,000
Exit 96 Corona ( SR-91 ) 184,000 182,000 187,000
Exit 106 Ontario ( SR-60 ) 225,000 215,000 219,000
Exit 109 Ontario ( I-10 ) 207,000 198,000 206,000
Exit 115 Rancho Cucamonga ( I-210 ) 151,000 134,000 140,000
Exit 123 San Bernardino ( I-215 ) 162,000 152,000 152,000
Exit 141 Hesperia ( US 395 ) 106,000 101,000 101,000
Exit 184 Barstow ( I-40 ) 67,000 65,000 66,000
Exit 246 Baker 40,000 40,000 42,000
Exit 296 border with Nevada 40,000 40,000 43,000

Lane Configuration

From Unpleasant Lanes Comments
Exit 1 Exit 3 2×3 San Diego
Exit 3 exit 12 2×5 San Diego
exit 12 exit 13 6+2+2+6
exit 13 Exit 19 5+2+2+5
Exit 19 exit 32 4+2+2+4
exit 32 exit 63 2×4
exit 63 Exit 91 2×3
Exit 91 Exit 96 4+1+1+4 express lanes through Corona
Exit 96 Exit 106 3+1+1+3 express lanes
Exit 106 Exit 122 2×4 Ontario
Exit 122 Exit 123 2×3
Exit 123 Exit 141 2×4
Exit 141 Exit 184 2×3 barstow
Exit 184 Exit 296 2×2 Mojave Desert

History of Interstate 15 in California