 In August 1851, Marquam moved to Portland, Oregon, then a small town of under 1,000 inhabitants.For many years he was the largest landowner in Multnomah County, Oregon, counting among his holdings Portland's Fulton District and his homestead on Marquam Hill in southwest Portland.The hill was part of a donation land claim he purchased for $2,500 in 1857 from John Donner, brother of George Donner of the ill-fated Donner Party.