Chronicling America: "Chronicling America . . . allows you to search and read newspaper pages from 1900-1910 and find information about merican newspapers published between 1690-present." This beta site from the Library of Congress digitizes selected newspapers from California, District of Columbia, Florida, Kentucky, New York, Utah, and Virginia and only for the first decade of the 20th century. At 100,000 pages for each state, the site holds three-quarters of a million pages of historic newspapers.
Chronicling America is exactly what the future of newspaper digitization should look like. It has a reasonably sophisticated search engine, allowing Boolean as well as keyword searching and searches for two words within 5 words of one another. Newspaper pages may be viewed in text (!) down loadable image, or PDF format. The site is responsive and search results and newspaper pages load briskly.
Unfortunately no Northwest newspapers are digitized as yet (unless we want to include San Francisco--do we?). However many northwest events may be investigated through the site--I got hits with such search terms as Chief Joseph, Edward Curtis, Spokane, and many others. To the left is one such story from the May 19, 1902 issue of The San Francisco Call about a threatening gold rush on the Spokane Reservation.