The Detroit-Windsor Tunnel and several heavily used roads in Detroit will be closed to motorists for part of Sunday for the 2025 Detroit Free Press Marathon.

Thousands of people are expected to take part in the full marathon, which runs through Detroit and Windsor, Ontario, Canada. There is also an international half-marathon and a 13.1-mile race held entirely within Detroit on Sunday.

Race organizers say the tunnel will be closed to all vehicle traffic from 6:30 a.m. to 10:30 a.m.

"Every year, the Tunnel becomes more than just a vital international crossing—it becomes a symbol of unity. We're honored to play a role in this world-class event that celebrates perseverance, partnership, and the spirit of both sides of the river," Regine Beauboeuf, CEO of the Detroit-Windsor Tunnel, said in a news release on Thursday.

According to the Detroit Free Press, roads along the course will begin closing as early as 4 a.m. on Sunday. 

Major roads impacted include Lodge Freeway, Michigan Avenue, West Fort Street and Woodward Avenue. Learn more about downtown Detroit driving routes and closures here.

The Ambassador Bridge will have two-way vehicle traffic on one side of the structure during the race, and runners will be on the other. Organizers say a buffer lane will separate the vehicle traffic and runners and that there may be delays for motorists using the bridge to travel to Detroit on Sunday morning.

The men's and women's race winners of last year's full marathon are a Ferndale, Michigan, couple. Sydney Devore-Bowman won the race in just over two hours and 42 minutes, and her husband, Andrew Bowman, completed the course in just over two hours and 17 minutes.