The Santa Rosa Marathon returns to local streets Sunday morning with more than 3,500 runners hitting the course for the 26.2-mile test of strength and endurance as well as the attendant events, a half-marathon and a downtown 5-K race.

Race organizers expect as many as 5,000 people to gather along the course to encourage the runners.

The event will impact local vehicle travel.

These are the schedule road closures:

<b>Downtown loop, generally within the boundaries of Fifth Street to the north, Mendocino Avenue to the west, Sonoma Avenue to the south and Hope Street to the east.</b>

Santa Rosa Avenue, 5-9 a.m.

Sonoma Avenue, 5-9 a.m.

E Street and D Street, 5-9 a.m.

First Street through Seventh Street, 5-9 a.m.

Mendocino Avenue from Seventh Street to Sonoma Avenue, 5-9 a.m.

<b>Note: </b>Brookwood and B Street will be open for drivers to proceed through the area.

<b>County loop</b>

This series of roads following the county portion of the marathon course and will be closed from 6-11 a.m.

Willowside Road

Guernville Road, 6-11 a.m. from Fulton past the Raley's supermarket to Lagune Frei Road.

Olivet Road

West Olivet Road

Oakwild Lane

Woolsey Road

Wood Road

Fulton Road will be one-lane south from Wood Road to Piner Road

<b>Note: </b>Through traffic to the west can use River Road or Hall