You never know from one election to the next which spot in a given state will have the most up-to-date information; it keeps changing. So we operate on a list of several, each election night. No real point in checking before 8 p.m. local time. Link list:
Secretary of State - usually one of the best, regionally as well as in Washington. Love their county-breakout results maps.
King County Elections - home of around half of Washington's ballots.
Seattle Times - general coverage plus numbers.
Secretary of State - not sure what they'll have on line tonight; historically, there's not been a lot of real-time data here. But check it out.
Multnomah County Elections - Notoriously late in processing, but check here to see how things will look on Wednesday.
Oregonian - Often the best real-time data comes via the Oregonian.
KGW-TV - This Portland station often has tightly-timed data as well.
Secretary of State - In the last couple of cycles the SoS has been posting good-time numbers. They advise that won't start till 9mtn/8pac.
Ada County Elections - a number of interesting race numbers should turn up here first.
Idaho Statesman - Some years they have the most up to minute numbers in the state (for statewide, and the southwest reaches of Idaho). Sometimes not.
KTVB-TV - Traditionally strong with election night numbers, though mileage varies.