Interstate 5 (I-5) is an Interstate Highway on the West Coast of the United States that serves as the region's primary north–south route. It spans 277 miles (446 km) across the state of Washington, from the Oregon state border at Vancouver, through the Puget Sound region, to the Canadian border at Blaine. Within the Seattle metropolitan area, the freeway connects the cities of Tacoma, Seattle, and Everett.
An Amtrak Cascades train running in the median of I-5 near Kalama. The route of the Cascades generally runs parallel to I-5 within Washington state.
A section of I-5 near downtown Tacoma, pictured in 2015 during an expansion project
I-5 and the Downtown Seattle skyline, as seen from Dr. Jose Rizal Park on Beacon Hill
The Ship Canal Bridge, which carries I-5 into the University District in Seattle
A high-occupancy vehicle lane is a restricted traffic lane reserved for the exclusive use of vehicles with a driver and at least one passenger, including carpools, vanpools, and transit buses. These restrictions may be only imposed during peak travel times or may apply at all times. There are different types of lanes: temporary or permanent lanes with concrete barriers, two-directional or reversible lanes, and exclusive, concurrent, or contraflow lanes working in peak periods.
A high-occupancy vehicle lane on Interstate 5 in Seattle
The first HOV freeway, which opened in 1969, was on Shirley Highway in Northern Virginia; as of 2012, the I-95/I-395 HOV facility operates as a two-lane barrier-separated reversible HOV 3+ facility (center lanes) with access through elevated on- and off-ramps.
For 50 years, from 1970 to 2020, the California Department of Transportation preferred to use the term "carpool", as seen on I-405 in Los Angeles, as opposed to "HOV".
The I-495 Capital Beltway in the Washington D.C. Metropolitan Area. The facility is located in the median, has two HOV lanes in each direction with elevated on/off ramp access with a total of 224.0 mi (360.5 km) of lanes.