[1] The company operated steamships between San Francisco and ports along the Columbia River at Astoria, Portland and The Dalles, serving the lumber and salmon fishing industries.

Principal shareholders included D. F. Bradford (one of the owners of the north bank portage railway at the Cascades), Jacob Kamm, Harrison Olmstead, Simeon G. Reed, R. R. Thompson, and steamboat captains John C. Ainsworth and L. W. Coe.

[4] These boats posed serious competition to the monopoly, so much so that in about 1864,[4] the Oregon Steam Navigation Company paid its rival $10,000 a year to confine its operations to the Willamette River.

[4] Traffic increased in the early 1860s, so in 1863 and 1864, OSN added the Nez Perce Chief, the Webfoot, the Owyhee and the Yakima, all built at Celilo on the upper Columbia, and the Mississippi-style side-wheeler Oneonta on the middle river.

In 1863, the company replaced the mule-drawn portage railway on the north side of the Cascades with a steam locomotive.

The company also built a 13-mile (21 km) steam railway from the Dalles around Celilo Falls, which opened on April 23, 1863 and cost $1 million to build.