The third annual San Luis Obispo Marathon is this weekend. Roads throughout the city will be closed from 4:00 a.m. until 2:00 p.m. Sunday for the full and half marathon. Race organizers and the city encourage drivers to use Highway 101 to travel between the north and south parts of the city. There are over 4,000 runners signed up for the race. The 5K and fun run will be at the Madonna Meadows on Saturday.