It bears repeating: Navigating roads in the metro area Sunday could be an endurance test.

Thousands of runners will make their way from downtown Minneapolis to downtown St. Paul during Sunday's Twin Cities Marathon, causing detours and closures.

Marathon officials suggest using Interstate 94 and I-35W in Minneapolis to bypass the racecourse. In St. Paul, motorists are advised to use I-35E, Ayd Mill Road or Grand Avenue to get around the finish line near the State Capitol.

Traffic will be able to cross the course at a few intersections — such as Lake Street near Lake Calhoun — at the discretion of course marshals.

A 10-mile run begins at 7 a.m. Sunday, and the marathon follows at 8, but road closures are already underway:

In St. Paul

John Ireland Boulevard and Kellogg Boulevard will be closed on from 7 to 11 a.m. Saturday.

John Ireland Boulevard and Summit Avenue to Pascal Street will be closed from 7:20 to 11:30 a.m. Saturday.

12th Street from Wabasha to John Ireland Boulevard will be closed from 7 a.m. to noon Saturday and 5 a.m. to 6 p.m. Sunday.

Summit between Ramsey Street and Portland Avenue will be closed from noon Saturday to 6 p.m. Sunday.

In Minneapolis

Downtown streets between 5th and 11th avenues and 6th to 3rd streets will be closed from 5 a.m. to 9 a.m. Other road closings along the route include:

Miles 0-1 — 7 to 8:45 a.m.

3-8 — 7:30 to 10:20 a.m.

8-12 — 7:30 to 11:15 a.m.

12-15 — 7:30 to noon

15-21 — 7 a.m. to noon.

21-26 — 7 a.m. to 2:30 p.m.