Oregon 126 replaced the routing of U.S. 126 in 1972. The state highway enters the metropolitan area from Florence and the Oregon coastline. Following West 11th Avenue, Oregon 126 enters the Eugene city limits near its intersection with Belt Line Highway. Belt Line Highway heads north to meet Oregon 99 near Eugene Airport. Oregon 126 meanwhile continues east into the residential areas of west Eugene.
The former U.S. 126 turns north onto Garfield Street from West 11th Avenue to make the leap to 6th & 7th Avenues. There Oregon 126 merges with Oregon 99 for the approach to Interstate 105 and downtown. Once the tandem reach Jefferson and Washington Streets, Oregon 126 departs the U.S. 126 routing for Interstate 105 east across the Willamette River. Oregon 126 Business continues east with Oregon 99 through downtown Eugene.
Interstate 105 and Oregon 126 venture north from the Downtown Eugene area to the Delta Highway and east from there to Interstate 5. Oregon 126 is fully signed along the overlap. Interstate 105 ends at Interstate 5 while Oregon 126 continues the freeway east into the city of Springfield. Oregon 126 Business follows Oregon 99 east along Franklin Boulevard its split at Interstate 5. The business route continues east into Glenwood and downtown Springfield via Main Street.
Despite being shown as a freeway all the way to Oregon 126 Business (Main Street), the Oregon 126 freeway at Springfield ends at the intersection with 52nd Street. From there the four-lane highway curves southeast as an expressway to Main Street. Oregon 126 departs Springfield along the McKenzie Highway.