Interstate 405 (California)

Interstate 405
Interstate 405
San Diego Freeway
	I-405 highlighted in red
Route information
	Auxiliary route of I-5
	Maintained by Caltrans
Length	72.15 mi (116.11 km)
Existed	1964–present
NHS	Entire route
Major junctions
South end	I-5 in Irvine
	SR 133 in Irvine; SR 55 / SR 73 in Costa Mesa; I-605 / SR 22 in Seal Beach; I-710 in Long Beach; I-110 in Carson; I-105 near LAX; I-10 in West Los Angeles; SR 2 in Westwood; US 101 in Sherman Oaks; SR 118 in Mission Hills;
North end	I-5 in Sylmar
Location
Country	United States
State	California
Counties	Orange, Los Angeles
Highway system
	Interstate Highway System; Main; Auxiliary; Suffixed; Business; Future; State highways in California; Interstate; US; State; Scenic; History; Pre‑1964; Unconstructed; Deleted; Freeways;

Interstate 405 (I-405, locally referred to as The 405^[2]) is a major north–south auxiliary Interstate Highway in Southern California. The entire route is known as the northern segment of the San Diego Freeway. I-405 is a bypass auxiliary route of I-5, running along the southern and western parts of the Greater Los Angeles urban area from Irvine in the south to Sylmar in the north.

I-405, heavily traveled by both commuters and freight haulers along its entire length, is the busiest and most congested freeway in the United States.^[3]^[4] The freeway's annual average daily traffic between exits 21 and 22 in Seal Beach reached 374,000 in 2008, making it the highest count in the nation.^[5] It has played a crucial role in the development of dozens of cities and suburbs along its route through Los Angeles and Orange counties. It also serves Los Angeles International Airport, Long Beach Airport, and Orange County's John Wayne Airport.

^ Starks, Edward (January 27, 2022). "Table 2: Auxiliary Routes of the Dwight D. Eisenhower National System of Interstate and Defense Highways". FHWA Route Log and Finder List. Federal Highway Administration. Retrieved March 19, 2023.
^ Richards, Gary (November 16, 2015). "Roadshow: Why 'The 405' is called 'The 405'". The Mercury News. Retrieved August 18, 2023.
^ "U.S. Highways With the Most Traffic". Time For Kids. Archived from the original on August 11, 2011.
^ Santa Monica College Corsair News Article Archived August 15, 2007, at the Wayback Machine
^ Office of Highway Policy Information (July 27, 2010). "Most Traveled Urban Highways Average Annual Daily Traffic". Federal Highway Administration. Retrieved January 26, 2013. {{cite web}}: |author= has generic name (help)

[1] Starks, Edward (January 27, 2022). "Table 2: Auxiliary Routes of the Dwight D. Eisenhower National System of Interstate and Defense Highways". FHWA Route Log and Finder List. Federal Highway Administration. Retrieved March 19, 2023.

[2] Richards, Gary (November 16, 2015). "Roadshow: Why 'The 405' is called 'The 405'". The Mercury News. Retrieved August 18, 2023.

[3] "U.S. Highways With the Most Traffic". Time For Kids. Archived from the original on August 11, 2011.

[4] Santa Monica College Corsair News Article Archived August 15, 2007, at the Wayback Machine

[5] Office of Highway Policy Information (July 27, 2010). "Most Traveled Urban Highways Average Annual Daily Traffic". Federal Highway Administration. Retrieved January 26, 2013. {{cite web}}: |author= has generic name (help)

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