Auburn is a city in Barrow and Gwinnett counties in the U.S. state of Georgia. As of the 2020 census, the city had a population of 7,495. A…Auburn is a city in Barrow and Gwinnett counties in the U.S. state of Georgia. As of the 2020 census, the city had a population of 7,495. Auburn incorporated in 1892 soon after the railroad was extended to that point.