I-5’s predecessors were US 99 and US 101. The southernmost section between the Mexico-Los Angeles border was preceded by US 101. Farther north from Los Angeles to the Oregon state border, it was US 99, although it ran further east in the San Joaquin Valley than I-5 was built later. The original US 99 in this area is now State Route 99. With the renumbering of 1964, US 99 disappeared completely from California and US 101 was shortened with a new starting point in Los Angeles.
San Diego – Irvine
The route from the border with Mexico to Irvine was originally part of US 101 and was numbered as such until 1964, when the number was shortened to Downtown Los Angeles. The oldest section of the highway is located in San Diego in the Chula Vista suburb, which opened in 1952. The highway between I-805 and National City was completed in 1955. The rest of the highway through the San Diego area was built in the 1960s. The last section opened in 1973 and was the border crossing with Mexico.
According to topschoolsintheusa.com, an HOV lane has been constructed 8 kilometers in both directions between Avenida Pico in San Clemente and San Juan Creek Road in San Juan Capistrano, with the highway widening to 2×5 lanes. The work was carried out in phases, the first phase started in February 2014. The project was completed on 29 March 2018.
Between 2017 and 2022, I-5 between Loma Santa Fe Drive in Solano Beach and Palomar Airport Road in Carlsbad was widened to 2×5 lanes over a length of 15 kilometers. The additional HOV lanes opened on February 15, 2022 for traffic heading north and on March 23, 2022 heading south.
Irvine – Los Angeles
The I-5 between Irvine and Los Angeles was originally also numbered US 101 until 1964. The Santa Ana Freeway is one of the oldest freeways in Los Angeles, the first part opened to traffic on the southeast side of Downtown Los Angeles in 1947. angeles. The highway as far as Santa Ana was completed in 1957, the last section opened to traffic in Tustin in 1958.
Los Angeles – Santa Clarita
I-5 at the Newhall Interchange with State Route 14.
I-5 through ‘The Grapevine’ north of Los Angeles.
North of Downtown Los Angeles, the route was part of US 99. The first section of the freeway opened to traffic in 1957 in Burbank. The highway was soon built through the San Fernando Valley and was completed in 1963 to the Newhall Interchange with State Route 14 at Santa Clarita.
Santa Clarita – Mettler
The route from Santa Clarita to Mettler runs over the 1,263 meter high Tejon Pass. The entire mountain range is also known as ‘The Grapevine’. The first road through the mountain range was called the Ridge Route and was completed in 1915 and completely paved in 1919. This was a simple road that followed the contours of the terrain, with as few excavations and bridges as possible. This section had 697 turns. In 1933 the ‘Ridge Route Alternative’ opened, a new route that largely had 3 lanes. This became US 99 and was widened to 4 lanes in the 1950s.
The first section of Interstate 5 opened in 1960 between Lebec and Wheeler Ridge. This includes the steep descent into the San Joaquin Valley. In 1967 the section opened over the Tejon Pass between Castaic and Gorman, including the change of direction. The rest also opened around that time, in 1968 the last link between Santa Clarita and Castaic opened. I-5 is built directly here with 2×4 lanes.
‘The Grapevine’ is one of the most famous highway routes in California. It is also a vulnerable route, there are no alternative connections. The old Ridge Route still exists but is no longer maintained and has been listed on the National Register of Historic Places since 1997. Most of the road is not open to traffic. However, most of I-5 has been built over the Ridge Route Alternative, making I-5 the only road connection in many parts between Santa Clarita and the San Joaquin Valley. During heavy snowfall, ‘The Grapevine’ is sometimes closed to traffic, meaning there is no longer a connection between Los Angeles and the San Joaquin Valley. Traffic to San Francisco will then have to take a detour via US 101 along the coast.
| From | Unpleasant | Length | Date |
| 207 Lebec | 219 Wheeler Ridge | 19 km | 00-00-1960 |
| Los Angeles County Line | 207 Lebec | 6 km | 00-00-1964 |
| 202 Gorman | Kern County line | 2 km | 00-00-1966 |
| 176 Castaic-Lake Hughes Road | 202 Gorman | 42 km | 00-00-1967 |
| 219 Wheeler Ridge | 221 | 3 km | 00-00-1967 |
| 162 | 167 Santa Clarita-Lyons Avenue | 8 km | 00-00-1967 |
| 167 Santa Clarita-Lyons Avenue | 176 Castaic-Lake Hughes Road | 14 km | 00-00-1968 |
San Joaquin Valley (Mettler-Manteca)
The route through the San Joaquin Valley, from its junction with State Route 99 near Mettler and the beginning of the Stockton urban area, near the town of Manteca, was originally controversial. The traditional north-south route through the San Joaquin Valley was US 99 (now SR-99) via Bakersfield and Fresno. Later it was decided to build an entirely new route through the western part of the valley. This was Interstate 5.
The highway has been built at a rapid pace, and the 390-kilometer route has actually been opened within 5 years. The first sections of the highway opened to traffic in 1966, the last section in 1971 and was the northern section in the Tracy region. I-5 was built much faster than parallel State Route 99, although portions of CA-99 are older.
| From | Unpleasant | Length | Date |
| 403 Los Banos (CA-33/152) | 407 Santa Nella Blvd (CA-33) | 6 km | 00-00-1966 |
| 365 Manning Avenue | 385 Nees Avenue | 32 km | 00-00-1966 |
| 407 Santa Nella Blvd (CA-33) | 445 | 61 km | 00-00-1967 |
| 319 Lassen Avenue (CA-269) | 334 Dorris Avenue (CA-198) | 24 km | 00-00-1967 |
| 262 7th Standard Road | 278 Lost Hills (CA-46) | 26 km | 00-00-1967 |
| 221 | 244 Taft Highway (CA-119) | 37 km | 00-00-1967 |
| 349 Derrick Avenue (CA-33) | 365 Manning Avenue | 26 km | 00-00-1967 |
| 334 Dorris Avenue (CA-198) | 349 Derrick Avenue (CA-33) | 24 km | 00-00-1968 |
| 244 Taft Highway (CA-119) | 262 7th Standard Road | 29 km | 00-00-1969 |
| 309 Kettleman City (CA-41) | 319 Lassen Avenue (CA-269) | 16 km | 00-00-1969 |
| 278 Lost Hills (CA-46) | Kings County line | 23 km | 00-00-1970 |
| Kern County Line | 309 Kettleman City (CA-41) | 27 km | 00-00-1971 |
| 385 Nees Avenue | 403 Los Banos (CA-33/152) | 29 km | 00-00-1971 |
| 445 | 461 | 26 km | 00-00-1971 |
Manteca – Sacramento
The route from Manteca to Sacramento passes through the town of Stockton. This part was opened in the 1970s. The first section opened in 1970 north of Downtown Stockton. The route through Stockton was completed in 1975 and the last section between Stockton and Sacramento opened in 1979. This was also the last section of I-5 to open between Los Angeles and Sacramento.
Between 2013 and 2016, Stockton widened I-5 from 2×3 to 2×4 lanes, with the additional lane being an HOV lane. The additional lanes opened to traffic on September 21, 2016. These were the first HOV lanes in the Stockton area.
| From | Unpleasant | Length | Date |
| 473 Stockton Park Street | 478 Stockton-Hammer Lane | 8 km | 00-00-1970 |
| 461 | 471 Stockton Taylor Street | 16 km | 00-00-1971 |
| 471 Stockton Taylor Street | 473 Stockton Park Street | 3 km | 00-00-1972 |
| 478 Stockton-Hammer Lane | 481 Stockton-8 Mile Road | 5 km | 00-00-1975 |
| 481 Stockton-8 Mile Road | 485 Lodi (CA-12) | 6 km | 00-00-1976 |
| 485 Lodi (CA-12) | 498 Twin Cities Road | 21 km | 00-00-1979 |
Sacramento
I-5 at I-80 in Sacramento.
The route through the capital Sacramento opened fairly quickly in the late 1960s and early 1970s. The first section opened in 1968 between Downtown Sacramento and the airport. The highway to Woodland was completed in 1969. The interchange opened with US 50 in 1970. The last sections south of Sacramento opened in 1974-1975.
| From | Unpleasant | Length | Date |
| 519 Downtown Sacramento | 528 Airport Boulevard | 14 km | 00-00-1968 |
| 528 Airport Boulevard | 537 Woodland Main Street | 14 km | 00-00-1969 |
| 518 | 519 Downtown Sacramento | 2 km | 00-00-1970 |
| 515 Sacramento-Sutterville Road | 518 | 5 km | 00-00-1971 |
| 512 Sacramento-Freeport Boulevard | 516 Sacramento-Sutterville Road | 6 km | 00-00-1974 |
| 498 Twin Cities Road | 512 Sacramento-Freeport Boulevard | 23 km | 00-00-1975 |
Sacramento Valley (Sacramento – Red Bluff)
The route through the Sacramento Valley, between the Sacramento region and the city of Red Bluff, opened primarily in the 1960s and early 1970s. In the early years between 1964 and 1968, the highway was mainly constructed from north to south. The last section to open was in Woodland in 1973.
| From | Unpleasant | Length | Date |
| 647 South Red Bluff | 650 Red Bluff – Adobe Road | 5 km | 00-00-1964 |
| 650 Red Bluff – Adobe Road | 652 Red Bluff – Wilcox Road | 3 km | 00-00-1965 |
| 631 Corning | 647 South Red Bluff | 26 km | 00-00-1965 |
| 601 South Willows | 631 Corning | 48 km | 00-00-1966 |
| 559 County Line Road | 575 Husted Road | 26 km | 00-00-1967 |
| 548 Zamora | 559 County Line Road | 18 km | 00-00-1968 |
| 538 Woodland-East Strete | 548 Zamora | 16 km | 00-00-1970 |
| 588 North Maxwell | 601 South Willows | 21 km | 00-00-1970 |
| 575 Husted Road | 588 North Maxwell | 21 km | 00-00-1971 |
| 537 Woodland Main Street | 538 Woodland East Street (CA-113) | 2 km | 00-00-1973 |
Northern California (Red Bluff – Oregon)
Interstate 5 in Northern California is significantly more fragmented than the rural parts between Sacramento and Red Bluff. The first short sections were laid as early as 1960, but it was not until the early 1970s before long sections of the highway could be driven through. In 1964 the mountainous section along Mount Shasta opened and in 1965 the section along Redding opened to traffic. In 1968 the section around Shasta Lake opened. North of Shasta Lake, the road has long been a divided highway with intersections. It was not until 1989-1991 that this part was made grade-separated. This was also the last section of Interstate 5 to open.
In 2011, I-5 between Cottonwood and Anderson was widened 5 kilometers to 2×3 lanes. Shortly thereafter in 2012, a portion of Interstate 5 was widened to 2×3 lanes a little further north through Redding. Between 2018 and 2022, the 11-kilometer intermediate section between Anderson and Redding has been widened to 2×3 lanes. The widening was completed on February 8, 2022. This provided 24 kilometers of I-5 with 2×3 lanes in the Redding region.
| From | Unpleasant | Length | Date |
| 723 Sweetbrier Avenue | 730 Dunsmuir | 12 km | 00-00-1960 |
| 747 Weed | 751 Edgewood Road | 6 km | 00-00-1960 |
| 714 Gibson Road | 723 Sweetbrier Avenue | 14 km | 00-00-1962 |
| 652 Red Bluff – Wilcox Road | 662 South Cottonwood | 16 km | 00-00-1963 |
| 662 South Cottonwood | 665 North Cottonwood | 5 km | 00-00-1964 |
| 734 Mott Road | 743 Mount Shasta | 14 km | 00-00-1964 |
| 670 Cascade | 681 North Redding | 18 km | 00-00-1965 |
| 730 Dunsmuir | 732 Dunsmuir Avenue | 3 km | 00-00-1966 |
| 665 North Cottonwood | 670 Cascade | 8 km | 00-00-1966 |
| 695 O’Brien | 702 Antler | 11 km | 00-00-1966 |
| 796 Hilt Road | Oregon state line | 2 km | 00-00-1966 |
| 681 North Redding | 695 O’Brien | 23 km | 00-00-1968 |
| 751 Edgewood Road | 770 Killgore Hills Road | 31 km | 00-00-1969 |
| 770 Killgore Hills Road | 786 Klamath River Road | 26 km | 00-00-1970 |
| 793 Bailey Hill Road | 796 Hilt Road | 5 km | 00-00-1971 |
| 702 Antler | 704 Lakehead | 3 km | 00-00-1972 |
| 743 Mount Shasta | 747 Weed | 6 km | 00-00-1973 |
| 786 Klamath River Road | 793 Bailey Hill Road | 12 km | 00-00-1974 |
| 732 Dunsmuir Avenue | 734 Mott Road | 3 km | 00-00-1976 |
| 710 Slate Creek | 714 Gibson Road | 6 km | 00-00-1989 |
| 704 Lakehead | 710 Slate Creek | 10 km | 00-00-1991 |
Future
Between 2019 and 2025, 11 miles of I-5 in Orange County will be widened from 2×5 to 2×6 lanes. It concerns the stretch from State Route 73 to El Toro Road in Laguna Beach. One general purpose lane will be added in both directions and the second HOV lane will be extended north to Alicia Parkway. The project will cost $581 million. Between 250,000 and 330,000 vehicles drive daily on this route. The project started on June 6, 2019 and should be completed by mid-2025.
Traffic intensities
| Exit | Location | 2007 | 2016 |
| Exit 1 | border with Mexico | 104,000 | 85,000 |
| Exit 9 | National City ( SR-54 ) | 188,000 | 190,000 |
| exit 13 | San Diego ( I-15 ) | 199,000 | 203,000 |
| Exit 16 | San Diego ( SR-163 ) | 213,000 | 229,000 |
| Exit 22 | San Diego | 226,000 | 219,000 |
| exit 38 | Solana Beach | 227,000 | 256,000 |
| Exit 71 | Camp Pendleton | 135,000 | 140,000 |
| Exit 79 | San Clemente ( SR-1 ) | 228,000 | 242,000 |
| Exit 86 | Laguna Niguel ( SR-73 ) | 265,000 | 287,000 |
| Exit 92 | Irvine ( I-405 ) | 347,000 | 355,000 |
| Exit 95 | Irvine ( SR-133 ) | 170,000 | 244,000 |
| Exit 102 | Tustin | 292,000 | 325,000 |
| Exit 107 | Santa Ana ( SR-22 / SR-57 ) | 350,000 | 366,000 |
| Exit 113 | Anaheim ( SR-91 ) | 224,000 | 241,000 |
| Exit 119 | Santa Fe Springs | 165,000 | 171,000 |
| exit 130 | East Los Angeles ( I-710 ) | 232,000 | 244,000 |
| Exit 134 | Los Angeles ( SR-60 ) | 264,000 | 250,000 |
| Exit 135 | Los Angeles ( I-10 ) | 243,000 | 234,000 |
| Exit 137 | Los Angeles ( SR-110 ) | 291,000 | 283,000 |
| Exit 144 | Glendale ( SR-134 ) | 273,000 | 258,000 |
| Exit 154 | Los Angeles ( SR-170 ) | 303,000 | 307,000 |
| Exit 162 | Santa Clarita ( SR-14 ) | 272,000 | 286,000 |
| Exit 172 | Santa Clarita ( SR-126 ) | 125,000 | 118,000 |
| Exit 222 | Mettler ( SR-99 ) | 75,000 | 88,000 |
| Exit 334 | Huron | 32,000 | 38,000 |
| Exit 446 | Vernalis ( I-580 ) | 20,000 | 43,000 |
| Exit 459 | Banta ( I-205 ) | 160,000 | 152,000 |
| Exit 471 | Stockton ( SR-4 ) | 140,000 | 138,000 |
| Exit 493 | Thornton | 57,000 | 51,000 |
| Exit 518 | Sacramento ( U.S. 50 ) | 156,000 | 156,000 |
| Exit 521 | Sacramento ( I-80 ) | 197,000 | 195,000 |
| Exit 525 | Sacramento ( SR-99 ) | 116,000 | 125,000 |
| Exit 537 | Woodland ( SR-113 ) | 34,000 | 38,000 |
| Exit 552 | Zamora ( I-505 ) | 24,000 | 36,000 |
| Exit 647 | Red Bluff | 28,000 | 34,000 |
| Exit 678 | Rescue | 68,000 | 67,000 |
| Exit 773 | Yreka | 15,000 | 17,000 |
| Exit 796 | border with Oregon | 15,000 | 17,000 |
Lane Configuration
| From | Unpleasant | Lanes |
| exit 0 | Exit 31 (I-805) | 2×4 |
| Exit 31 (I-805) | exit 33 | 2×8 |
| exit 33 | Exit 34 | 2×6 |
| Exit 34 | exit 37 | 2×5 |
| exit 37 | Exit 74 | 2×4 |
| Exit 74 | Exit 82 | 2×5 |
| Exit 82 | exit 85 | 2×6 |
| exit 85 | Exit 95 | 2×5 |
| Exit 95 | Exit 114 | 2×6 |
| Exit 114 | Exit 122 | 2×3 |
| Exit 122 | Exit 130 (I-710) | 2×4 |
| Exit 130 (I-710) | Exit 135 (I-10) | 2×5 |
| Exit 135 (I-10) | Exit 137 | 2×4 |
| Exit 137 | Exit 144 | 2×5 |
| Exit 144 | Exit 153 | 2×4 |
| Exit 153 | Exit 156 | 2×5 |
| Exit 156 | Exit 158 (I-405) | 2×4 |
| Exit 158 (I-405) | Exit 162 | 2×5 |
| Exit 162 | Exit 202 | 2×4 |
| Exit 202 | Exit 222 | 2×3 |
| Exit 222 | Exit 459 (I-205) | 2×2 |
| Exit 459 (I-205) | Exit 461 | 2×5 |
| Exit 461 | Exit 471 | 2×3 |
| Exit 471 | Exit 476 | 2×4 |
| Exit 476 | Exit 485 | 2×3 |
| Exit 485 | Exit 508 | 2×2 |
| Exit 508 | Exit 513 | 2×3 |
| Exit 513 | Exit 526 | 2×4 |
| Exit 526 | Exit 673 | 2×2 |
| Exit 673 | Exit 680 | 2×3 |
| Exit 680 | Exit 796 | 2×2 |
