Princeton is a city in Mille Lacs and Sherburne counties in the U.S. state of Minnesota. It is located at the confluence of the Rum River and its West branch. The population was 3,933 at the 2000 census. Nearly all residents live within Mille Lacs County. U.S. Route 169 and Minnesota State Highway 95 are two of the main arterial routes in the city.