Winnsboro is a town in, and the parish seat of Franklin Parish, Louisiana, United States. As of 2020, its population was 4,862. Franklin Parish …Winnsboro is a town in, and the parish seat of Franklin Parish, Louisiana, United States. As of 2020, its population was 4,862. Franklin Parish was created on March 1, 1843, from portions of Ouachita, Catahoula, and Madison parishes through the efforts of Louisiana Senator John Winn. Land for a centrally located parish seat, Winnsborough, was purchased in 1844. It was designated as the parish seat of government in 1846 and incorporated on March 18, 1902.