By air: Seattle-Tacoma International Airport (SEA) — universally called Sea-Tac — is 14 miles south of downtown on I-5, and is the main gateway for the Pacific Northwest. It handles direct flights from most major North American cities and has substantial international service including direct routes to Europe, East Asia, and Australia. Alaska Airlines is the dominant carrier and uses Sea-Tac as its hub.
The cheapest and most reliable connection to downtown is the Sound Transit Link Light Rail, which runs directly from the airport to downtown Seattle (Westlake Station) in about 38 minutes. Trains run every 8–15 minutes and cost around $3.25. Take the Link; do not take a cab from the airport unless you are travelling in a group with significant luggage.
By train: Amtrak operates two Seattle routes from King Street Station, a handsome Beaux-Arts building at 3rd Avenue South and Jackson Street. The Cascades corridor runs north to Vancouver, BC (3.5 hours) and south to Portland (3.5 hours) and Eugene, with several daily trains in each direction. The Coast Starlight runs south to Los Angeles (35 hours) via Portland, Sacramento, and the California coast — one of the great scenic rail journeys in North America, though schedules are unreliable. The Empire Builder runs east to Chicago (46 hours) along the Columbia River Gorge.
By bus: Greyhound, FlixBus, and BoltBus serve Seattle from Portland and other Pacific Coast cities. The Pacific Coach Lines runs to Vancouver, BC. Buses arrive at various downtown locations.
By car: Seattle is on I-5, the main Pacific Coast north-south interstate. Portland is 3 hours south; Vancouver, BC is 3 hours north. Traffic in and around Seattle is notoriously heavy during commuting hours; check conditions before entering the city.