Petersburg is a rural unincorporated community and census-designated place in Boone County, Kentucky, United States. As of the 2020 census Petersburg, along with its surrounding areas that use the 41080 zip code, had a population of 500. It is located 25 miles away from Cincinnati, Ohio. Archaeological evidence reveals an ancient Indian settlement was located at Petersburg town site. The first white settlement at Petersburg was Tanner's Station, an outpost founded before 1790.