"I'm ecstatic," Humphries said in a release. "Our goal all year was to win world championships and we did it. This is the perfect end to a great season and to do it in St. Moritz is the ultimate for any bobsledder.
"People don’t understand what this place means to us athletes. It is the birthplace of our sport and the longest track in the world that demands experience and skill so it means the world to me to win the world championships here."
Americans Elana Meyers and Katie Eberling claimed silver with a time of 4:30.99, while Germany's Sandra Kiriasis and Franziska Bertels earned bronze at 4:31.01.