From Ancestry.com Wiki
Southport is a town in Lincoln county, Maine. It was formed in 1842. Southport began keeping vital records in 1842 and town records in 1842. For more information, contact the county at 361 Hendricks Hill Rd./Box 149, Southport 04576. On the attached map, Southport is shown as 18 in Lincoln county.
For information about the state of Maine see Maine Family History Research.