Interstate 405 (California)
Interstate 405 (I-405, locally referred to as The 405) 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.
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 | |||
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| North end | I-5 in Sylmar | |||
| Location | ||||
| Country | United States | |||
| State | California | |||
| Counties | Orange, Los Angeles | |||
| Highway system | ||||
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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. 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. 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.