Question: The 2170 mile Oregon Trail connected various towns along a 150 mile long valley, forms the cultural and political heart of Oregon, and is home to three of Oregon's largest cities, including which city that is the state capital?

Context paragraphs:
Goodale's Cutoff: Goodale's Cutoff formed a spur of the Oregon Trail beginning in Idaho, United States.  The cutoff left the trail near Fort Hall, crossed the Snake River Plain to the Lost River, and then turned west to the area of Boise, crossing Camas Prairie.  It rejoined the main trail from Ditto Creek to Boise, then ran to the north of the main trail, crossing the Snake River into Oregon at Brownlee's Ferry.  In Oregon travelers could now reach the Eagle Valley and Pine Valley areas, and the gold mines in Auburn.  The cutoff rejoined the main Oregon Trail at the Powder River, near Baker City.

Williamsburg Mountain: Williamburg Mountain is actually a high "S" bend in the 150 mile long, Tussey Mountain ridge.

Oregon Trail, Wells Springs Segment: The Oregon Trail, Wells Springs Segment, also known as the Oregon Trail, Boardman Bombing Range Segment, is part of an historic east–west migration route crossing Morrow County in the U.S. state of Oregon.  About 250,000 emigrants from the United States used the trail between 1841 and 1846 to travel between the U.S. state of Missouri and the Willamette Valley in western Oregon.

Register Cliff: Register Cliff is a sandstone cliff and featured key navigational landmark prominently listed in the 19th century guidebooks about the Oregon Trail, and a place where many emigrants chiseled the names of their families on the soft stones of the cliff it was one of the key checkpoint landmarks for parties heading west along the Platte River valley west of Fort John, Wyoming which allowed travelers to verify they were on the correct path up to South Pass and not moving into impassable mountain terrainsgeographically, it is on the eastern ascent of the Continental divide leading upward out of the great plains in the east of the U.S. state of Wyoming.  It is notable as a historic landmark for 'registering' hundreds of emigrants on the Oregon Trail (thus also the other northern Emigrant Trails that split off farther west such as the California Trail and Mormon Trail) who came to follow custom and inscribed their names on its rocks during the western migrations of the 19th century.  An estimated 500,000 emigrants used these trails from 1843–1869, with up to one-tenth dying along the way, usually due to disease.

Willamette Valley: The Willamette Valley ( ) is a 150 mi long valley in the Pacific Northwest region of the United States.  The Willamette River flows the entire length of the valley, and it is surrounded by mountains on three sides – the Cascade Range to the east, the Oregon Coast Range to the west, and the Calapooya Mountains to the south.  It forms the cultural and political heart of Oregon, and is home to approximately 70 percent of its population including its three largest cities: Portland, Eugene and Salem, the state capital.

Salt Lake Cutoff: The Salt Lake Cutoff is one of the many shortcuts (or cutoffs) that branched from the California, Mormon and Oregon Trails in the United States.  It led northwest out of Salt Lake City, Utah and north of the Great Salt Lake for about 180 mi before rejoining the California trail near the City of Rocks, Idaho.  From there Oregon Trail travelers could easily travel down the Raft River valley portion of the California Trail to return to the Oregon Trail.  It provided a way to stop in Salt Lake City (the only significant city on the trail then) for repairs, fresh supplies, fresh livestock etc..  In later years it was used by tens of thousands of pioneers and miners going east and west on their way to or from the future states of California, Oregon, Utah, Idaho, Montana, Nevada or Washington.

Camp Walbach: Camp Walbach, some 25 miles Northwest of Cheyenne, Wyoming and directly west of the crossing at the head of Lodge Pole Creek was established to guard and protect the emigrants through Cheyenne Pass, a dangerous spot on the new Overland Trail.  Established as a military post September 20, 1858; abandoned, April 19, 1859.  Named for General J. B. Walbach, who said at the time the camp was constructed: "This was the route which should have been adopted when the road was changed from the Sweetwater and South Pass in 1862," meaning changing from the Oregon Trail to the Overland Route.  After going through Cheyenne Pass, the emigrants were soon on the Laramie Plains, where this trail connected and became a part of the Overland Stage Route from the south.  This road was never a mail route, but strictly and exclusively one for emigrants, who were driven from the Oregon Trail, unless in caravans, by the hostility of the Native Americans.

Oregon Trail School District: The Oregon Trail School District is a public school district in the U.S. state of Oregon.  It spans 424 sqmi from the outskirts of the city of Gresham to the top of Mount Hood, on the Oregon Trail.  It encompasses several distinct, mostly unincorporated, rural areas of Clackamas County, including the communities along the Mount Hood Corridor, Boring, and the city of Sandy.  The district serves approximately 4,200 students.  There are five elementary schools, three middle schools, Oregon Trail Academy, a K-12 IB charter school, and one high school, Sandy High School.

Route of the Oregon Trail: The historic 2170 mi Oregon Trail connected various towns along the Missouri River to Oregon's Willamette Valley.  It was used during the 19th century by Great Plains pioneers who were seeking fertile land in the West and North.

Oregon Trail: The Oregon Trail is a 2170 mi historic east–west, large-wheeled wagon route and emigrant trail in the United States that connected the Missouri River to valleys in Oregon.  The eastern part of the Oregon Trail spanned part of the future state of Kansas, and nearly all of what are now the states of Nebraska and Wyoming.  The western half of the trail spanned most of the future states of Idaho and Oregon.

Supporting paragraphs: Route of the Oregon Trail Willamette Valley
Answer: Salem