California Highways:
www.cahighways.org

No Current Routing.

▸In 1963, this route was defined to run from Route 91 near Corona to Route 15 [now I-215] near Devore, passing near Milliken Avenue at its junction with Route 10.

Construction occurred in phases. The northern interchange between I-15 and Route 31 was budgeted for construction during the 1967-68 Fiscal Year, including construction of about 1.8 mi of the route S from the interchange. By 1970, it was completed S to Cajon Blvd. During 1972 mainline I-15 was realigned onto the partially completed freeway corridors of Route 31 and Route 71 south of Corona.  A letter from the California State Highway Engineer dated February 28, 1972, noted the request to shift the mainline corridor of I-15 to Route 31 and Route 71 had been submitted to the Federal Highway Administration during July 1971.  The Federal Highway Administration approved the change of alignment for I-15 on January 24, 1972 as chargeable mileage.
(Source: Gribblenation Blog (Tom Fearer), "Former California State Route 31", 12/1/2023)

▸In 1974, Chapter 537 transferred this segment to Route 15. Hamner Avenue was signed as "Temporary I-15" once I-15 was constructed south to Route 60 in 1980 (it had reached I-10 a year earlier). Prior to that Route 31 signage existed along Hamner as well as its Milliken Ave. extension in eastern Ontario north of there. Route 31 signage was largely removed (except for a few "straggler" signs in Corona and Norco) when the temporary I-15 signage was erected. That temporary signage extended south of Route 91 as well along then-Route 71 to the original 4-lane freeway section from south Corona to north of Lake Elsinore. That segment got actual I-15 signage circa 1979-80. One of the last Route 31 signs was a trailblazer just before the EB Route 91/NB Route 31/Temp I-15 loop ramp (prior to the interchange's reconstruction as a wide diamond in the late '80's); that sign had been there since first erected back in 1968.
(Source: Scott Parker on AARoads, July 2018)

Some significant history of this route is discussed under I-15. The following is an excerpt:

Scott Parker (Sparker) on AAroads provided an even more detailed history in a post on 7/12/2016:

It all started with the I-15 extension south to San Diego, part of the 1968 1500-mile Interstate expansion legislation. Originally, the concept was to take I-15 directly south from the original I-10 junction at Colton, continue south on the ridge between Reche Canyon and Pigeon Pass, and then descend the mountain near the present east junction of Route 60 and I-215, and then segue onto what was then US 395 south past March AFB and on to San Diego. That concept didn't last long—just as long as it took to do a detailed survey of the proposed route—the mountains in that area are basically a pile of unstable compressed sandstone "rocks"; a construction nightmare. A more "flatland" approach was explored to the west, diverging from US 395 between Grand Terrace and Highgrove (both between Colton and Riverside), heading south east of Iowa Avenue, then following the Santa Fe rail line along the base of the mountains—directly behind UC Riverside—and merging with Route 60/US 395 (now Route 60/I-215) just north of the present route split in Moreno Valley. You can guess how that went over with the UC Riverside community—it would have wiped out a whole nest of apartments serving as student housing—not to mention being across the street from the Chancellor's official residence! By the end of 1969, that option was also kaput.

Early in 1970 District 8 planners came up with an alternate that solved more than a few issues -- the proposed Route 31 freeway, extending north from Corona through eastern Ontario before turning northeast along the base of the San Gabriel mountains to intersect I-15 at Devore, the point where the route started climbing Cajon Pass. Realigning I-15 over this route would cut about 23 miles off the Los Angeles-Las Vegas I-10/I-15 routing by eliminating the "backtracking" route via San Bernardino. And, lo and behold, the south end of the Route 31 freeway continued south of Corona as the Route 71 proposed freeway (actually, about 10 miles of it had been constructed circa 1967 between Corona and Lake Elsinore), which itself merged with US 395 at Murietta, just north of Temecula. While about ten miles longer than the existing I-15/US 395 route through Riverside and Perris, this reroute concept drew not only attention from the local press but also that in L.A.—virtually all favorable to the idea. By mid-1970 the Division of Highways had decided to strongly pursue the Route 31 option. AASHTO (at that time, without the first "A") concurred, and the matter reached FHWA by the beginning of fall.

At first, FHWA raised an objection to the funding of the former Route 31 section from I-10 north to the existing I-15 at Devore because of the existence of the in-place I-15 through San Bernardino, which had been previously the recipient of chargeable Interstate funds. But a perusal of the records showed that the segment between I-10 and 5^th Street in San Bernardino had commenced construction in early 1956— almost a year before Interstate funds were first disbursed; only the segment north of there was actually part of chargeable construction. Negotiations commenced, and an agreement was finally made near the end of 1970 whereby California would waive any rights to Interstate maintenance or reconstruction funds for the original I-15 segment between I-10 and Devore in exchange for full funding of the entire Route 31/Route 71 corridor as the realigned I-15. Once that agreement was finalized, the Division accelerated construction of the Devore freeway-to-freeway interchange, already in progress as part of the I-15 Cajon realignment, along with the first couple of miles of the new (then) Route 31 alignment, which opened by the spring of 1971 (this was pre-STIP days, when the Division could do such things without much in the way of outside interference).

However, as soon as the dust had settled on the reroute, the cities of San Bernardino and Riverside voiced concerns that this new routing, which completely bypassed their city centers, would have a negative effect on their development plans. Together, these cities had devised a plan whereby the new western route via Corona and Ontario would become I-15W, while US 395 would be renumbered I-15E, regardless of the actual non-Interstate status of the latter route—but keeping an Interstate route through their midst. AASHTO quickly shot down the full E/W split, but reserved the notion of at least keeping US 395 through San Bernardino signed as an Interstate until the Ontario-Devore segment of the new alignment could be completed. And as this was several years prior to the decision to eliminate suffixed Interstate numbers, they approved the signage of the I-10 to Devore segment as I-15E (the Division had the entirety of US 395 from Murietta to Devore redesignated as an unsigned Route 194, a number previously decommissioned elsewhere). Initially, I-15E was intended to be a purely temporary designation—but that it existed at all (signed as such in late 1972) placated the city of San Bernardino for the time being.

However, the city of Riverside did not hesitate to voice their objections to being left out of the Interstate network. They "lucked out", however due to inadvertently good timing: the Nixonian "block grant" legislation, passed in early 1973 prior to that administration's functional crippling in the wake of the Watergate scandal, introduced the concept of "chargeable/nonchargeable" Interstate delineation. Now the 15E concept could, with AASHTO/FHWA consent, be extended south along US 395, rejoining the new I-15 at Murietta, as a nonchargeable route. With a major push from the local Congressional delegation, this was done by the spring of 1974. I-15E was signed in place of US 395 as far south as the Route 60 split at Moreno Valley; the remainder of the route south to Murietta was signed, by mid-1975, as "Temporary I-15E" and south of the Route 71 merge at Murietta as "Temporary I-15". This configuration lasted for a few years until the decision to eliminate suffixes was made.

Renumbering of the completed and uncompleted portions of I-15E was proposed circa 1979; Caltrans made one of their rare appropriate renumbering decisions: to reinstate the number 215, which was an urban surface-street connector in Pomona before it was deleted from the state highway system in 1965. AASHTO and FHWA vetted the 15E to 215 change by 1981; the renumbering in the field took place in 1982. Although some sections were technically substandard, the route was by that time mostly full freeway; a short segment between Sun City and Perris still featured a couple of at-grade crossing roads, while the segment from Perris to Route 60 was still a divided facility with numerous at-grade and/or signalized intersections [Ed: I remember this segment from numerous trips to OERM in Perris]. The "temporary" designation concept had been dropped by Caltrans at that point; the section between the Murietta I-15 divergence and Route 60 was (IMO somewhat absurdly) signed as "TO I-215" northbound, and as Route 215, complete with green shields, southbound. This unwieldly situation persisted until the two sections featuring cross traffic were upgraded to full freeway in 1995. The in-city Riverside segment of I-215 featured one of the most underpowered Interstate "Turn Off To Stay On" (TOTSO) interchanges (in both directions, including a 25mph loop southbound) until 2004, when the southbound I-215 2-lane flyover was completed; the northbound outside ramp still shrinks to a single lane before merging with lanes continuing from the terminating Route 91. It's still a TOTSO—but not quite as obnoxious as before!
(Source: Scott Parker @ AAroads, "Re: Interstate 15E signage in San Bernardino and Riverside Counties?", 7/12/2016)

The route of 1964-1974 Route 31 was LRN 193, defined in 1933 by Chapter 767 as "[LRN 77] near Prado to [LRN 9] near San Bernardino" to the highway system. In 1935, this was added to the highway code as LRN 193, with the definition "[LRN 77] near Prado to [LRN 9] near San Bernardino".

The 1935 Division of Highways Maps of San Bernardino County and Riverside County display the early alignment of LRN 193.  Within San Bernardino County, LRN 193 branched east from LRN 77 (Sign Route 71) at the site of what is now the Prado Reservoir.  LRN 193 followed modern McCarty Road, Cucamonga Avenue and Chino-Corona Road into Riverside County. Upon entering Riverside County, LRN 193 followed Chandler Street, Harrison Street, Citrus Street, Cleveland Avenue and Riverboat to Adams Avenue (now Hamner Avenue) north of Norco.  From the Norco Area, LRN 193 followed Adams Avenue and Bellgrave Avenue to LRN 19 (US 60 on Mission Boulevard) east of Mira Loma.  From the Mira Loma area, LRN 193 branched northeast from LRN 19 via Armstrong Avenue back into San Bernardino County.  Upon reentering San Bernardino County, LRN 193 followed Armstrong Road and Cedar Avenue to LRN 26 (US 99/US 70 on Valley Boulevard) in Bloomington.  From Bloomington, LRN 193 followed Bloomington Avenue and Riverside Avenue to LRN 9 (US Route 66 on Foothill Boulevard) in Rialto.
(Source: Gribblenation Blog (Tom Fearer), "Former California State Route 31", 12/1/2023)

Later in 1935, Chapter 493 changed the route to: "[LRN 43] at Corona northerly to [LRN 19]". This change truncated both ends of the route. It moved the southern end to the northeast, from roughly the Route 91/Route 71 junction to Route 91/Hamner Av in Corona. The route then ran up Hamner and Milken, originally to US 66 (LRN 9), but that was truncated to US 60 (LRN 19).

In 1959, Chapter 1062 relaxed the routing and extended the route to [LRN 31] near Devore: "[LRN 43] at near Corona northerly to [LRN 19] [LRN 31] near Devore."

In 1962, Legislative Chapter 2089 defined a new LRN 30 as running from US 99/US 70/I-10 at LRN 26 to US 66/US 91-395/I-15 at LRN 31.  The corridor of LRN 30 duplicated the already existing extension of LRN 193 to LRN 31 near Devore.  The LRN 30 designation had previously been used as part of the Oroville-Quincy Highway that served as early Sign Route 24 before construction of the Feather River Highway.  Also in 1962, the California Highway Commission adopted a planned alignment for the Devore Cutoff Freeway (LRN 193/LRN 30) during their June meeting.  The Devore Cutoff Freeway began near Devore and extended south to Norco.  In 1963, the California Highway Commission adopted an altered planned alignment for LRN 193 near Corona. 
(Source: Gribblenation Blog (Tom Fearer), "Former California State Route 31", 12/1/2023)

Sign Route 31 was not defined as part of the original set of state signed routes. It is unclear what, if any, routing was signed as Sign Route 31 before 1964.

• California @ AARoads: California 31
• Gribblenation Blog (Tom Fearer): Former California State Route 31
• Roadgap: The Mass Grave: CA 7, CA 14U, CA 31 (and TEMP I-15), US 60, US 91, CA 195 (Cameron Kaiser)

The route that would become LRN 31 was first defined in the 1916 Second Bond Act as "an extension of the San Bernardino county state highway lateral to Barstow in San Bernardino County by the most direct and practical route..." (i.e., US 66 to Barstow). In 1925, the route was extended to Nevada by Chapter 369, which authorized and directed "the California highway commission to acquire necessary rights of way, and to construct and maintain a highway, which is hereby declared to be a state highway, extending from Barstow...to a point...on the boundary line between the state of California and the state of Nevada...which said highway is commonly known and referred to as the Arrowhead trail.". In 1933, the route was extended again with a segment from "[LRN 26] near Colton to [LRN 9] near San Bernardino via Mt. Vernon Ave".

In 1935, LRN 31 was codified into the state highway code as:

1. San Bernardino to the Nevada State Line near Calada, via Barstow
2. [LRN 26] near Colton to [LRN 9] near San Bernardino via Mt. Vernon Avenue

This was primary state highway from San Bernardino to the Nevada State Line.

In 1957, Chapter 1911 removed the branch on Mt. Vernon Avenue, which appears to have been signed as US 395/US 91. That segment was subsequently rerouted onto a new alignment for LRN 43. The specific dividing point between LRN 31 and LRN 43, post 1957, is less clear: it likely was LRN 9 (US 66), but could have been LRN 190 (Sign Route 30).

Signage on the route was as follows:

1. Between LRN 26 (US 99/US 70) and LRN 9 (US 66): Cosigned US 91/US 395. This later became I-15E and then I-215. Sign Route 18 was not on this segment; it was signed along the LRN 26 from Colton and LRN 43 N of LRN 9.  Note that this segment of LRN 31 went away after 1957; US 395 / US 91 moved to the new LRN 43 freeway (although the old signage may have remained during construction).
2. Between LRN 9 (US 66) and Verdemont/Devore: Cosigned as US 91/US 66/US 395. This later became I-15E and then I-215. Sign Route 18 was not on this segment; it was signed along the LRN 26 from Colton and LRN 43 N of LRN 9. With the completion of the LRN 43/LRN 31 freeway, US 395 / US 91 moved onto the new freeway. It is unclear, from the maps, if US 66 moved off of LRN 31 at this time. It is possible that US 66 was signed on both the freeway and the older LRN 31 surface street routing. With the completion of the LRN 43/LRN 31 freeway (I-215), it appears the divergence between LRN 43 and LRN 31 occurred at the point where today's Route 259 splits from I-215: LRN 43 continued along Route 259, with LRN 31 starting at that point and continuing as US 91 / US 395 / US 66.
3. Between Devore and 7 mi SW of Victorville: The route was cosigned as US 66/US 91/US 395. This is present-day I-15. US 395 (LRN 145) diverged and headed N at this point.
4. Between 7 mi SW of Victorville and Barstow: The route was cosigned as US 91/US 66. This is present-day I-15. At Barstow, US 66 (LRN 58) diverged and headed E.
5. Between Barstow and the Nevada state line: The route was cosigned as US 91/US 466. This is present-day I-15.

Additional San Bernardino Notes

The original LRNs in San Bernardino were equally convoluted according to Scott Parker (Sparker). The "spine" LRN through the region was LRN 43, which followed Sign Route 18 throughout the region; a number of long-distance LRNs terminated at this legislative route. LRN 26 was US 99 south of the 3^rd Street/E Street intersection, following US 99 all the way to the Mexican border at Calexico. LRN 31, which carried US 66 over Cajon Pass to Barstow, and US 91 (which was not extended south of Barstow until 1947) northeast from there to Nevada, began at the junction of Mt. Vernon and 3^rd Street and was the Mt. Vernon RR bridge and US 66 east from there. LRN 9 was US 66, and originally US 99, extending west from LRN 31 on 4^th Street toward Pasadena. Sign Route 30/Highland Ave. was LRN 190, and North E Street and Kendall Ave. Business US 66 was LRN 191.

Scott Parker (Sparker) noted in that discussion that this arrangement didn't last long; the bridge over the Santa Ana River connecting Colton Ave. in the south reaches of San Bernardino with Valley Blvd. in central Colton was completed circa 1931; LRN 26 and US 99 were rerouted west along that alignment. South E Street from the rerouted US 99/LRN 26 became a realigned but unsigned LRN 43. 3^rd Street, still carrying Sign Route 18, became an eastern extension of LRN 9, which terminated at 3^rd and E Street at LRN 43 (Sign Route 18 still turned north there). The entirety of Mt. Vernon north of Valley Blvd. in Colton was reassigned to LRN 31; it still carried Sign Route 18 south of 3^rd Street until US 395 was commissioned in 1934 to join it. US 99/LRN 26 continued west from Colton on Valley Blvd. into Ontario, where it was renamed Holt Ave.

Similar to 4^th street west of Mt. Vernon, 3^rd Street past the original Santa Fe depot (now used by Metrolink & Amtrak) east of the Mt. Vernon bridge features portions of the original segmented concrete pavement that once carried US 99 & Signed Route 18. The east-west Valley Blvd. alignment that eventually became US 99/LRN 26 was in place as a county facility at the time US 99 was routed through central San Bernardino, with its east end at or near Mt. Vernon Ave. in Colton. The delay involved with realigning US 99 was due to the difficulty experienced in constructing bridges over the Santa Ana River; the riverbed consists of deep layers of sand and silt lying in scooped-out sandstone with no supporting bedrock to speak of. Bridge construction over such a "waterway" required placing concrete caissons deep into the sand and waiting for them to settle before constructing bridge piers upwards from them -- then letting the whole assembly settle even more before extending a bridge deck over the piers. This method has continued to this day; the I-10, I-215, and Route 210 bridges over the Santa Ana River were deployed in a similar manner. The original US 99 E Street bridge was the only exception; it was a relatively light "trestle" structure sitting atop the silt layers; it was replaced by the present caisson-based structure in the mid-'60's, a few years after the original I-10 and I-15 (now I-215) bridges were built.
(Source: Scott Parker (Sparker) @ AAroads, 7/7/2016)

LRN 31 was part of the Arrowhead Trail (Ocean to Ocean Trail) along the portion of the route from Las Vegas to where US 66 exited to the West. This includes the original routing through the Bannock Cutoff, the later routing through Yermo, and the final routing through Daggett into Barstow.

The portion of LRN 31 between Barstow and San Bernardino was part of the National Old Trails Road.

This route (both present-day Route 66 and as historic US 66) was part of the "New Santa Fe Trail".

This route (both present-day Route 66 and as historic US 66) appears to have been part of the "National Park to Park Highway", and the "Pikes Peak Ocean to Ocean Highway".

• ⦅Routing⦆
• ⦅Post 1964 Signage History⦆
• ⦅Pre 1964 Signage History⦆
• ⦅Other WWW Links⦆
• ⦅Pre-1964 Legislative Route⦆
• ⦅Acronyms and Explanations⦆