California State Route 166

State Route 166
Maricopa Highway
Route information
Defined by S&HC § 466
Maintained by Caltrans
Length:	95.886 mi[1] (154.314 km) SR 166 is broken into pieces, and the length does not reflect the US 101 and SR 33 overlaps that would be required to make the route continuous.
Major junctions
West end:	SR 1 in Guadalupe
	US 101 in Santa Maria SR 33 in Maricopa
East end:	SR 99 at Mettler
Highway system
State highways in California(list • pre-1964) History • Unconstructed • Deleted • Freeway • Scenic ← SR 165 SR 167 →

State Route 166 (SR 166) is a state highway in the U.S. state of California. It connects the Central Coast to the southern San Joaquin Valley.

This route is part of the California Freeway and Expressway System^[2] and is eligible for the State Scenic Highway System^[3].

Route description

Route 166 starts off in Guadalupe in northwestern Santa Barbara County and heads east towards the largest city on its eastern journey: Santa Maria. It then joins with U.S. Route 101 for the last few miles in Santa Barbara County before crossing the Santa Maria River and splitting off in San Luis Obispo County. For the next 75 miles (121 km), SR 166 crosses the Santa Barbara/San Luis Obispo county line a total of five times. This stretch follows the Cuyama River through a canyon separating the Sierra Madre Mountains from mountains in San Luis Obispo County, and then opens out into the Cuyama Valley, passing cattle ranches, going through the Russell Ranch Oil Field, and passing Aliso Canyon Road, the turnoff to the South Cuyama Oil Field. On the north during this stretch is the mile-high Caliente Range, which contains Caliente Mountain, the highest peak in San Luis Obispo County.

After going through the towns of New Cuyama and Cuyama, the highway meets SR 33 north of Ventucopa. SR 33 and SR 166 merge until reaching Maricopa, where SR 166 heads due east for its last 20 miles (32 km), intersecting with I-5 9 miles (14 km) north of the Grapevine. SR 166 ends at SR 99 in Mettler, and it is the last exit for both I-5 and SR 99 southbound before they merge near Wheeler Ridge.

The western terminus of Route 166 snakes through the Guadalupe-Nipomo Dunes, which end at the Pacific Ocean

Before 1964, the portion of SR 166 merged with SR 33 was part of US 399.

In Kern County, Highway 166 is known as the Maricopa Highway. West of Maricopa, where it skirts Santa Barbara and San Luis Obispo counties, it is called the Cuyama Highway. In the cities of Santa Maria and Guadalupe, it is known as Main Street.

From US 101 to the junction of SR 33, 166 is signed as the "CHP Officers Irvine and Stovall Memorial Highway". In February 1998 a large storm swelled the Cuyama River and caused it to wash out a section of the highway. Officers Britt Irvine and Rick Stovall were responding to an early morning call about a truck accident when their CHP cruiser drove off the washed out section, overturned and was buried in mud.^[1]

Major intersections

Note: Except where prefixed with a letter, postmiles were measured in 1964, based on the alignment as it existed at that time, and do not necessarily reflect current mileage. The numbers reset at some county lines; the start and end postmiles in each county are given in the county column.

County	Location	Postmile [1][4][5]	Exit [6]	Destinations	Notes
Santa Barbara SB 0.00-90.99[N 1]	Guadalupe	0.00		West Main Street	Continuation beyond SR 1
		0.00		SR 1
	Santa Maria	7.87		SR 135 (Broadway, US 101 Bus.)
		8.93 88.60[N 1]		US 101 south / Main Street	Interchange; west end of US 101 overlap
		West end of freeway on US 101
		89.69[N 1]	172	Donovan Road
		90.75[N 1]	173	SR 135 south (Broadway, US 101 Bus. south) – Santa Maria
San Luis Obispo SLO 0.00[N 1]-22.89	East end of freeway on US 101
		0.81[N 1] 13.51		US 101 north / Cuyama Lane	Interchange; east end of US 101 overlap
Santa Barbara SB 22.89-R34.99	No junctions
San Luis Obispo SLO R34.99-R51.09	No junctions
Santa Barbara SLO R51.09-R70.14	No junctions
San Luis Obispo SLO R70.14-4.95[N 2]		74.72 2.80[N 2]		SR 33 south – Ojai, Ventura	West end of SR 33 overlap; former US 399 south
Kern KER 0.00[N 2]-24.62				Cerro Noroeste Road – Mount Abel Recreation Area
				Soda Lake Road – Soda Lake, California Valley	Serves Carrizo Plain National Monument
	Maricopa	R11.56[N 2] 0.01		SR 33 north (California Street) – Central District, Taft	East end of SR 33 overlap; former US 399 north
		14.86		Old River Road – Old River
		22.80		I-5	Interchange
	Mettler	24.62		Mettler Frontage Road West – Mettler
		24.62		SR 99 – Los Angeles, Bakersfield	Interchange; former US 99
1.000 mi = 1.609 km; 1.000 km = 0.621 mi      Concurrency terminus •      Closed/Former •      Incomplete access •      Unopened

1. ^ ^{a b c d e f} Indicates that the postmile represents the distance along US 101 rather than SR 166.
2. ^ ^{a b c d} Indicates that the postmile represents the distance along SR 33 rather than SR 166.

References

1. ^ ^{a b} California Department of Transportation, State Truck Route List (XLS file), accessed February 2008
2. ^ CA Codes (shc:250-257)
3. ^ CA Codes (shc:260-284)
4. ^ California Department of Transportation, Log of Bridges on State Highways, July 2007
5. ^ California Department of Transportation, All Traffic Volumes on CSHS, 2005 and 2006
6. ^ California Department of Transportation, California Numbered Exit Uniform System, U.S. Route 101 Freeway Interchanges, Retrieved on 2009-02-07.