The nation’s largest relay series will be coming through Skagit County Friday and Saturday. Some roads will have extra traffic as runners use them for the race.

The Ragnar Relay Northwest Passage, a 189-mile overnight relay race will begin in Whatcom County Friday morning, and end in Island County Saturday night. Teams of 12 athletes will run relay-style as they pass through Skagit County. More than 1,700 runners are expected to participate in the race.

The following Skagit County cities will have heavy traffic due to the relay race Friday and Saturday:

Bow — 1:30 p.m. Friday to 2 a.m. Saturday — Colony Road, Cuckanut Drive, Bow Hill Road, Mac Taggart Avenue, Gilkey Avenue, Farm To Market Road, Bayview-Edison Road, Josh Wilson Road, Higgins Airport Way, Steele Road and Westar Lane.

Burlington — 4:30 p.m. Friday to 3:30 a.m. Saturday — Peterson Road, South Norris Street, West Fairhaven Avenue, East Fairhaven Avenue, South Anacortes Avenue, East Whitmarsh Road, Burlington Boulevard, Riverside Drive and Stewart Road.

Mount Vernon — 5:30 p.m. Friday to 4:30 a.m. Saturday — Freeway Drive, Cameron Way, West Fir Street, North Forth Street, South Second Street, South First Street, West Division Street, South Ball Street, South Baker Street, Garfield Street, South Wall Street, McLean Road and Bradshaw Road.

La Conner — 6 p.m. Friday to 5 a.m. Saturday — Calhoun Road, Chilberg Road, Morris Street, North Sixth Street, Centre Street, South First Street, Caledonia Street, Maple Avenue and Pioneer Parkway Road.

Anacortes — 8:30 p.m. Friday to 7:30 a.m. Saturday — Fidalgo Bay Road, 36th Street, Commercial Avenue, 34th Street, 30th Street, T Avenue, R Avenue, 20th Street, I Avenue, 22nd Street, Island View Place, 21st Street, D Avenue, 12th Street, Oakes Avenue, Sunset Avenue, Anaco Beach Road and Marine Drive.

For more information on road traffic in Whatcom and Island counties visit http://www.ragnarrelay.com or call 877-83-RELAY.