A former course began on 5th Avenue N. between Harrison and Mercer Streets in front of the Museum of Pop Culture on the eastern edge of the Seattle Center campus, followed 5th Avenue through Downtown and the International District to Interstate 90, followed I-90 across Lake Washington to Mercer Island, turned around and headed back across the Homer M. Hadley Memorial Bridge to the shoreline, followed Lake Washington Boulevard S. to Seward Park, looped Bailey Peninsula, and followed Lake Washington Boulevard S. back up the shoreline to McGilvra Boulevard E. in Madison Park.

[10] The 2018 marathon course began on 5th Avenue N and Harrison Street near the Space Needle, and ended in the nearby Memorial Stadium.

[11] The marathon continued west largely on the trail until hitting a turnaround point near 8th Avenue NW, and then headed back south across Lake Union via the Aurora Bridge to finish in Memorial Stadium.

The course travels east and south across the University of Washington campus via Stevens Way and Rainier Vista to cross the Montlake Bridge.

The course then turned north onto State Route 99 through Woodland Park and circled Green Lake before returning to the highway.

To earn the Quadzilla medal, a runner must instead complete the It's Beginning to Look a Lot Like Christmas pop-up race.