There's a cool Web site that lets you look at the electoral college results in presidential races since 1789. It features a U.S. map that shows the color of states as they were carried every four years: red for Republican, blue for Democrat, purple for Whig. It's fun to look at the Great Nearby and see the trends.
Since 1988, Washington and Oregon have been in lockstep, going for the Democratic candidate in the last five presidential elections, but it wasn't always so. Oregon has been a strongly Republican state throughout its history, going red in 18 elections since 1892. And going back to 1860, it was red consistently, with the exception of 1868 when the voters were apparently fed up with the shenanigans of the Grant administration's scandals and went for Democrat Horatio Seymour. Oregon has gone blue 11 times since 1892, most of that during the FDR years and the last 20 years.
In contrast, Washington state has been just a bit more of a maverick, going red 14 times in the same time period (1892 was its first presidential election as a state). It's gone blue 14 times, preferring, when Oregon did not, Hubert Humphrey ('68), Harry Truman ('48), Woodrow Wilson ('16) and Williams Jennings Bryan (1896). Washington also bolted for a third party and boosted Teddy Roosevelt and the Bull Moose Progressives in 1912, the only northwest state to do so. Strangely, the color picked by the mapmakers for Teddy's Progressives is yellow, hardly suited to a saber-rattling Rough Rider.
Despite today's bluer hue in Washington and Oregon, there have been times when the entire Northwest corner — Washington, Oregon, Montana, Idaho, and Alaska (after statehood) — have gone solid red: 1984 and 1980 (Reagan), 1976 (Ford), 1972 and 1960 (Nixon), and 1956 and 1952 (Eisenhower) for example. The last time the greater region went all blue: the 1964 Lyndon Johnson landslide.
The site includes historical footnotes such as when an elector voted for someone who didn't win the popular vote. In 2004, a Minnesota elector, apparently in error, voted for John Edwards both for president and vice president. Voting incompetence gets kind of scary when even electors can't get it right.