Duluth is a city in Gwinnett County, Georgia, United States. Located north of Interstate 85, it is approximately 22 miles northeast of Atlanta. As …Duluth is a city in Gwinnett County, Georgia, United States. Located north of Interstate 85, it is approximately 22 miles northeast of Atlanta. As of the 2020 census, Duluth had a population of 31,873, and the United States Census Bureau estimated the population to be 31,864 as of 2021.