Hamlin is a city in Brown County, Kansas, United States. As of the 2020 census, the population of the city was 25. Hamlin was laid out in 187…Hamlin is a city in Brown County, Kansas, United States. As of the 2020 census, the population of the city was 25. Hamlin was laid out in 1870. It was named in honor of Hannibal Hamlin, Abraham Lincoln's vice-president.