Its construction allowed covered wagons to cross the Cascade Range and reach the Willamette Valley, which had previously been nearly impossible.

[2] Before the opening of the Barlow Road, pioneers traveling by land from the east followed the Oregon Trail to Wascopam Mission (now The Dalles) and floated down the Columbia River to Fort Vancouver, then a perilous and expensive journey.

It was also possible to drive livestock over Lolo Pass on the north side of Mount Hood, but that trail was too rugged for vehicles and unsuitable for wagons.

A trading post (allowed by the Department of War) had been built where river crossings could be made along with the disassembly of wagons to make rafts suitable for floating down the remainder of the Columbia.

[citation needed] The Barlow Road begins at Wascopam Mission and heads south to Tygh Valley (some consider Tygh Valley the origin), then turns west and roughly parallels the White River on the north and then west, crosses the south shoulder of Mount Hood at Barlow Pass, follows Camp Creek and the Sandy River for some way, and finally leads to Oregon City.

Barlow forged on with a train of seven wagons, intending to return for river transport if the mountain passage proved impractical.

[3] On October 1, 1845, Barlow and three men scouted ahead of their company and entered Mount Hood's foothills from the east near Tygh Creek, about 35 miles (56 km) from the mouth of the Deschutes River.

They thought they had glimpsed the Willamette Valley, and learned from the Indigenous people in the region of a trail leading to Oregon City, but returned to Tygh Creek about five days after their departure.

Permission was granted with a vote of 8-2 on December 17, 1845,[7] approved by Speaker pro-tem Henry A. G. Lee, and signed into law by Governor George Abernethy.

Barlow's estimate of $4000 (equivalent to $131,000 today[10]) had underestimated the number of trees to be cut down and forgotten the numerous challenging bridges that would have to be built over rivers such as the Sandy, Zigzag, White, and Salmon.

Despite the expense and difficulties of passage, the road was very popular, with more than a thousand immigrants and approximately 150 wagons recorded in the first year of operation.

[15] Approximately three-quarters of the settlers entering the Willamette Valley traveled the Barlow Road,[16] with most of the remainder choosing the Columbia River route.

East of the summit the Barlow Road has been in disuse for many years for a considerable distance down the eastern slope, especially where it traversed the canyon of White River.

[18]The construction of the Barlow Road contributed more towards the prosperity of the Willamette Valley and the future State of Oregon, than any other achievement prior to the building of the railways in 1870.

[9] A roadside marker and trail at Laurel Hill (just west of Government Camp) provides history and access to the portion where a sixty percent grade was present in the early Barlow Road.