Interstate 405 Oregon
Overview
Built in 1973, the double deck Fremont Bridge carries Interstate 405 and U.S. 30 over the Willamette River north of the Pearl District in Portland. Supporting 6,000 tons on its center span, the Fremont Bridge is the longest tied arch bridge in the world.1 08/27/06
The Stadium Freeway, Interstate 405 is a short urban loop encircling Downtown and the Pearl District in Porland west of the Willamette River. I-405 overlaps with U.S. 30 across the Fremont Bridge to I-5 at the Boise and Eliot neighborhoods. The south end of the freeway ties into the Marquam Bridge taking Interstate 5 northeast from the South Waterfront area to East Portland.
U.S. 26 westbound briefly overlaps with I-405 north from the SW 6th Avenue entrance ramp to Exit 1 D for Sunset Highway west. U.S. 26 eastbound follows I-405 south from Sunset Highway to SW Broadway at Exit 1 C. U.S. 26 (Sunset Highway) extends west across the Tualatin Mountains to the city of Beaverton along a freeway.
History
Construction on the Stadium Freeway began in 1964. Interstate 405 opened south of the Fremont Bridge on February 25, 1969. The tied arch bridge across the Willamette River opened on November 11, 1973. Costing $121 million, I-405 was the single most expensive Interstate Highway construction project in Oregon.2
Route Information
Source: December 31, 2021 Interstate Route Log and Finders List
I-405 Annual Average Daily Traffic (AADT)
1965 Gousha map showing Interstate 405 under construction south of the Portland city center.
Interstate 405 completed north to Montgomery Street in Portland on the 1968 Oregon Official Highway Map
 Photo Guides
North End
– Portland, Oregon
North
East at
South at
North
West at
North End Throwback
South End
/ Marquam Bridge – Portland, Oregon
South
East at
North at
South at
Sources:
http://egov.oregon.gov/ODOT/HWY/GEOENVIRONMENTAL/ docs/Historic_Bridge/Willamette_Fremont_Bridge.doc- Interstate 50th Anniversary: The Story of Oregon’s Interstates.
Page updated February 1, 2024.