Seattle Marathon organizers expect 15,000 participants for this year's event on Sunday.

The course starts near Seattle Center at 5th and Harrison, next to the Experience Music Project. Entrants will travel through downtown streets, along the shores of Lake Washington, through the Arboretum and back to the Seattle Center.

Streets will be closed in many areas around the city. Expect delays along the course and be prepared to follow detours.


The majority of the streets along the 26-mile course will be closed from 6:30 a.m. - 2:15 p.m., with streets at the beginning of the course opening earlier.

Your best bet would be to use I-5 to bypass local street closures.

  • Streets adjacent to the Seattle Center, including Mercer Street and Fifth Avenue N, will close at 5 a.m. and reopen at the conclusion of the marathon, at approximately 2:15 p.m.
  • The I-90 express lanes will be closed between Seattle and Mercer Island from 4 a.m. - 11:30 a.m.
  • The I-5 express lanes will be closed until 9:30 a.m., when they will reopen to southbound traffic.
  • The northbound I-5 off-ramp to Lakeview Boulevard will be closed from 7 a.m. to 4 p.m.
  • The westbound SR 520 exit to East Roanoke Street will be closed from 7 a.m. to 3 p.m.

Affected Streets Map

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