Merrill is a city in Lincoln County, Wisconsin, United States. The population was 10,146 at the 2000 census. The city is located to the south of and adjacent to the Town of Merrill. The Merrill area had a 2000 census population of 16,289, and comprises the core of the United States Census Bureau's Merrill mSA, which includes all of Lincoln County . Together with the Wausau MSA it forms the Wausau-Merrill CSA. As of the 2000 census, the CSA's total population was 155,475.