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DENVER — Sunday’s forecast is going to be perfect for people participating in the Colfax Marathon. The damp, cool conditions are exactly what some veteran runners say they like.

Thousands of runners from 47 states and a number of countries will descend on Denver for Sunday’s race. It’s a 26.2 mile run that goes up and down what is often touted as America’s main street

In addition to the full-length marathon, there are 5-kilometer, 10-mile and half-marathon runs.

Early Sunday morning, participants will make their way to City Park for the start of the 13th Colfax Marathon.

“It’s Denver’s only marathon,” Marathon CEO Andrea Dowdy said.

Because the race goes up and down a major road, traffic could be an issue Sunday morning. Drivers should prepare for road closures and delays along the race route.

A map of the route can be found by clicking here.

While most of the race is along Colfax Avenue, runners will also cruise through downtown and around Sloan’s Lake Park.

“Basically Havana out to Wadsworth, no don’t be on Colfax in the morning,” Dowdy said.

“Its more than just a race, it’s a community,” Patrick Rizzo, a veteran runner said.

Patrick Rizzo has ran the race for more than 10 years. This year he is expected to finish first in the half marathon race.

“I travel around the country and around the world racing and I can say very few have the atmosphere that this race has,” Rizzo said.