California Highways: 
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Routing
From Route 101 to Tiburon.
Post 1964 Signage HistoryThis definition remains unchanged from 1963. This is via Tiburon Blvd.
It appears that one rationale for this route may have been to support an
additional bay crossing. Marin County representatives had been working for
a second crossing to San Francisco since the 1940s, and elected
assemblycritters from the area supported the cause in 1950. In 1955, the
legislature appropriated $50,000 for a formal engineering study of a
bridge via Angel Island; and in 1956, the design and location of a span
crossing Angel Island and landing on the Tiburon peninsula won federal
approval. However, most Tiburon homeowners, including influential Marin
Conservation League president and wealthy philanthropist Caroline
Livermore, supported a plan to make Angel Island a state park. Arguing
that a bridge landing would ruin the island’s potential for
recreational use, they convinced state Department of Parks and Recreation
officials to oppose it. Citizens from both sides of the bay staged
protests, organized committees, and formed action groups, succeeding in
delaying state construction plans. It is likely that the crossing fed into
future planning for Route 131, it it was the likely N terminus of such a
crossing.
(Source: "REVOLT AGAINST SPRAWL: Transportation and the Origins of the Marin County Growth-Control Regime" (paywall), Louise Nelson Dyble, University of Southern California, Journal of Urban History, Vol. 34 No. 1,
November 2007, via Anneliese Agren, 11/15/2023)
Pre 1964 Signage HistoryThis route was LRN 52, defined in 1919. It was not a signed route before 1964.
Sign Route 131 was not defined as part of the initial state signage of routes in 1934. It is unclear what (if any) route was signed as Sign Route 131 between 1934 and 1964.
StatusTiberon Blvd Improvements
In October 2023, it was reported that plans are in the
works to repair and upgrade about 4.6 miles of Tiburon Boulevard. The
project, estimated to cost around $23 million, would take about a year and
be completed in three segments — the western, central and eastern
parts — beginning in spring of 2026. The plan calls for upgrading or
replacing guardrails, road signs, and drainage and electrical systems. It
also includes upgrading curbside ramps to be compliant with the Americans
with Disabilities Act, repaving roads and the addition of bike lanes. The
western segment of the project, spanning from Tower Drive in Mill Valley
to Reed Ranch Road in Tiburon, includes changes to two intersections. At
East Strawberry Drive, the right turn lane onto eastbound Tiburon
Boulevard would be removed and the existing bus stop on Tiburon Boulevard
would be relocated. The new bus stop would be coordinated with transit
authorities during the final design phase in the summer of 2025. Class IV
bikeways would be added along Tiburon Boulevard, from approximately 1,000
feet west of the freeway to Trestle Glen Boulevard. A class I bikeway at
East Strawberry Drive to Greenwood Cove Drive is also planned. The central
section of the project, spanning from Reed Ranch Road to San Rafael
Avenue, includes adding a class IV bike lane from Reed Ranch Road to
Trestle Glen Boulevard. The Avenida Miraflores/Tiburon Boulevard
intersection would be altered to remove the right turn lane from westbound
Tiburon Boulevard onto northbound Avenida Miraflores. The eastern section,
from San Rafael Avenue to the Tiburon Boulevard/Main Street intersection,
includes a curb extension at the Mar West Street intersection. It also
would add yield lines to the Ned’s Way/Tiburon Boulevard
intersection. After the public comment period ends, Caltrans will either
grant environmental approval, conduct additional environmental studies or
abandon the project. The project also requires approval from agencies such
as the state Department of Fish and Wildlife and the California
Transportation Commission.
(Source: Marin I-J, 10/31/2023)
In April 2024, it was reported that the CTC has
allocated $4.4 million for a plan to repair and upgrade Tiburon Boulevard
from the US 101 interchange to Main Street in Tiburon. The commission also
approved $1.7 million to support the construction of a retaining wall
against the hill on the north side of Tiburon Boulevard east of Trestle
Glen Boulevard. The largest project of the bunch is a $23 million
effort to improve Tiburon Boulevard with bicycle lanes and pedestrian
upgrades. The project is expected to be completed in three segments
beginning in January 2026 and lasting about a year. The plan calls for
upgrading or replacing guardrails, road signs and drainage and electrical
systems. It also includes upgrading curbside ramps to be compliant with
the Americans with Disabilities Act, repaving roads and adding bike lanes.
The western segment of the project, from Tower Drive in Mill Valley to
Reed Ranch Road in Tiburon, includes changes to two intersections. At East
Strawberry Drive, the right turn lane onto eastbound Tiburon Boulevard
would be removed and the existing bus stop on Tiburon Boulevard would be
relocated. Class IV bikeways would be added along Tiburon Boulevard from
approximately 1,000 feet west of the freeway to Trestle Glen Boulevard. A
class I bikeway at East Strawberry Drive to Greenwood Cove Drive is also
planned. The central section of the project, spanning from Reed Ranch Road
to San Rafael Avenue, includes adding a class IV bike lane from Reed Ranch
Road to Trestle Glen Boulevard. The Avenida Miraflores and Tiburon
Boulevard intersection would be altered to remove the right turn lane from
westbound Tiburon Boulevard onto northbound Avenida Miraflores. The
eastern section, from San Rafael Avenue to the intersection of Tiburon
Boulevard and Main Street, includes a curb extension at the Mar West
Street intersection. It also would add yield lines to the Ned’s Way
and Tiburon Boulevard intersection.
(Source: Marin I-J, 4/2/2024)
In August 2025, it was reported that Caltrans’
latest repaving plan for Tiburon Boulevard will not include bike lanes on
a mile-long stretch between Trestle Glen and Blackfield Drive. The plan
includes new bike lanes across the US 101 overpass and into the Strawberry
neighborhood. Final design plans for the full project were still
forthcoming, with the datedependent on comments from stakeholders. The
$12.7 million paving and upgrade project has been in development since
2023. The California Transportation Commission is expected to approve the
project in October 2025. Construction would begin in 2026.
(Source: Marin I-J, 8/19/2025)
In October 2025, the CTC approved the following
construction phase allocation for a 2024 SHOPP project: $18,527,000.
04-Mrn-131 0.0/4.392. PPNO 04-2904N; ProjID 0418000221; EA 1Q230. Route 131 In and near Tiburon, from Route 101 to Main Street. Rehabilitate
pavement, upgrade guardrail, rehabilitate drainage systems, upgrade curb
ramps to Americans with Disabilities Act (ADA) standards, construct Class
II and IV bikeways as complete streets elements, and apply pavement
delineation. This project will extend the pavement life and improve ride
quality. CEQA - ND, 01/23/2024; Re-validation 09/22/2025. NEPA - CE,
01/23/2024; Re-validation 09/22/2025. Sixteen month allocation time
extension for CONST and CON ENG approved under Waiver 24-125; August 2024.
Future consideration of funding approved under Resolution E-24-14; March
2024. Pre-Construction Phase: Budgeted (Actual, if different):
PA&ED $2,612,300 ($2,585,004); PS&E $4,226,000 ($3,021,457);
R/W Sup $158,000 ($144,228). Construction Phase -
Programmed (Allocation, if different): CON ENG
$3,341,000; CONST $12,762,000.
(Source: October 2025 CTC Agenda, Agenda Item 2.5b.(1) #8)
In November 2025, it was reported that Caltrans was
moving ahead with a second phase of upgrading Tiburon Boulevard. Caltrans
has indicated they will repave the Tiburon Peninsula’s main
thoroughfare in 2026, and add pedestrian improvements and bike lanes
— except for excluding the lanes on a mile-long stretch between
Trestle Glen Boulevard and Blackfield Drive. The decision by Caltrans over
the summer to exclude bike lanes from that stretch was controversial,
pitting cycling advocates against local officials who oversaw school bus
service and public transit. Other bike lane opponents included residents
who feared they would add to traffic congestion. At the time, Caltrans
said it would split the project into two phases and pledged the second
phase would begin with public forums and convening a task force where
improvements, such as paved islands for school bus stops and additional
upgrades to bike lanes, could be discussed. Caltrans’ commitment to
a second phase starting with a public engagement process drew praise.
(Source: Marin I-J, 11/17/2025)
Other WWW Links
StatisticsOverall statistics for Route 131:
Pre-1964 Legislative RouteIn 1933, Chapter 767 defined the route “[LRN 4] near Kingsburg to [LRN 10] near Lemoncove” as a state highway. It was codified in 1935 in the highway code as LRN 131 with the definition:
This is present-day Route 201 between Kingsburg and Elderwood, and Route 216 between Woodlake and Lemon Cove. The Route 245 portion between Elderwood and Woodlake was LRN 129; the LRN 130 routing in the area is unclear.s
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Maintained by: Daniel P. Faigin
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Route 130
Route 132