About 3 miles (5 km) north of the California border, the highway crosses 4,310 foot (1,314 m) Siskiyou Summit, the highest point on I-5. Dropping down into Rogue River valley through Oregon's southern mountains and towns such as Ashland, Medford and Grants Pass. Turning north across three passes to the Umpqua Valley and through Roseburg, the mountains tend to turn into hills, and as it reaches Cottage Grove, the road enters the Willamette River Valley. At Eugene the highway intersects with the short Interstate 105. The interstate then heads almost due north, skirting Albany and Corvallis, and passes through Salem. There were plans to build a spur into Salem, Oregon, called Interstate 305.
In downtown Portland, I-5 runs adjacent to the Willamette River and passes by the Rose Garden Arena (center), and Oregon Convention Center (right).Just north of Salem, between mile marks 259 and 260 (closer to 260), placed in the median is a sign where the 45th parallel crosses I-5. It bears the words "45 Parallel half way between the Equator and the North Pole".
The highway then tracks a little to the northeast, Interstate 205 splits off south of the Portland metro area. From here it passes up through Tualatin and Tigard along former U.S. Route 99W before hitting the southern terminus of I-405 and the Marquam Bridge. Also planned was a spur in Portland off of I-405, called Interstate 505, but it was never built and has been removed from city plans. A stub of I-505 exists as a long exit ramp to U.S. Route 30.
After crossing the Willamette River on the Marquam Bridge, I-5 has junctions at the western terminus of Interstate 84 and the northern terminus of I-405. It then continues through the northern parts of the city of Portland, and crosses into Washington via the Interstate Bridge.
Interstate 5 Oregon Descriptions - I-5.mobi
