The 21st annual 3M Half Marathon is set for Jan. 25, and event organizers are advising motorists to avoid certain roadways during the Sunday morning race. This year's marathon is expected to draw up to 6,500 participants throughout parts of Northwest and CentralAustin. Several road closures are anticipated throughout the city on Jan. 25: Capital of Texas Hwy./Loop 360 from MoPac to US 183 will be closed from 3-8 a.m. Stonelake Boulevard and Braker Lane in the Arboretum area will also be closed during that time Longhorn Boulevard, Industrial Terrace and United Drive will be closed from 5:45-10 a.m. Martin Luther King Jr. Boulevard between San Jacinto Boulevard and Congress Avenuewill be closed from 6 a.m. until noon 17th Street and Congress Avenue where the finish line is located will be closed between 4 a.m. and 12:30 p.m. Roads reopen as the last runner passes each intersection, according to event organizers. Recommended north-south alternative routes include I-35, North Lamar Boulevard and MoPac, and eastbound-westbound motorists are encouraged to use US 183, 15th Street, Cesar Chavez Street and Riverside Drive. The city of Austin has a full list of road closures available here. Participants are urged to allow additional time to reach the event's starting point at least 30 minutes prior to the start of the race, which begins at 7 a.m. and runs until 11 a.m.