Reddit reviews Atlas of Oregon, 2nd Ed

Hmm, I've slowly learned from many sources, mostly books. And more about Washington/Seattle, since I live there—although Oregon has a rich tradition of being interested in its history. For online stuff there's

• HistoryLink; Washington-centric; has hundreds of articles on many topics.
  
  
• Oregon Historical Society; (OHS) Oregon-centric.
  
  OHS publishes the Oregon Historical Quaterly. I think at least some of that is online. They also publish a mighty place name tome, with more detail than you probably ever want to know about Oregon place names: Oregon Geographic Names. But it isn't online and is expensive to buy new. I found a used copy for cheap though.
  
  
• BC Geographic Names is BC's place name database. Some pages have tons of info about a particular place name. Some pages have very little. Kinda hit and miss.
  
  
• The Volcanoes of Lewis and Clark is a surprising detailed USGS website about more than just volcanoes.
  
  
• Columbia River History.
  
  
• Center for Columbia River History.
  
  For books, some of which are previewable on Google Books:
  
  
• Historical Atlas of the Pacific Northwest, by Derek Hayes, is very good and covers the whole PNW, from Alaska to California to Montana and more.
  
  
• The Atlas of Oregon is very good, although it is only has a couple of history sections. Also it is expensive (again, can be found used for not too much). Obviously Oregon-centric.
  
  
• Murray Morgan's Skid Row and Puget's Sound are about Seattle and Tacoma respectively (or more generally north and south Puget Sound area).
  
  
• Native Seattle, by Coll Thrush, is an excellent Seattle-centric book about the long history of Indians and Seattle (and beyond, ie, the famous totem pole in Pioneer Square is from Alaska).
  
  
• Range of Glaciers, by Fred Beckey, is a hugely detailed history focused on the exploration and survey of the North Cascades. Everything you could possibly want to know about the US-Canada border survey through the mountains—exciting, right? But also lots of stuff about early fur traders, gold prospectors, railroads, etc.
  
  
• The Great Columbia Plain, by D.W. Meinig, focused on eastern Washington and northeast Oregon.
  
  There are many books about the very early history of Spanish exploration, British fur trading, and so on. Many are poorly written or very scholarly. A few I've liked:
  
  
• At the Far Reaches of Empire, by Freeman Tovell. Focused on the life of Juan Francisco de la Bodega y Quadra, who was the Spanish commander on Vancouver Island in the late 1700s, when war with Britain almost broke out over events there, and when George Vancouver came by, etc. This book gives a good picture of the peak of Spain's reach into the PNW. Spanish PNW history kinda got the shaft by British and American historians. We remember Captain Cook and Vancouver but not people like Bodega y Quadra and Malaspina. Yet Bodega y Quadra's accomplishments exceed Vancouver's, I think, and he was all around a better person; and Malaspina's was similar to Cook in many ways.
  
  
• The Nootka Connection, by Derek Pethick, is a somewhat drier, and more British/Canadian-centric account of the late 18th century ship-based stuff, detailing the Russian, Spanish, British, American, French, etc, ships that explored the PNW coast. He wrote another book, First Approaches to the Northwest Coast, that covers a slightly earlier period.
  
  
• Trading Beyond the Mountains, by Richard Mackie, focuses on the land-based fur trade that dominated the PNW from the 1790s to the mid-1800s. Mackie focuses on the British fur traders, who basically controlled the PNW until about 1840.
  
  Finally, there are hundreds of good references on some Wikipedia pages, like Columbia River and Maritime Fur Trade.