Detailed Instructions: In this task, you're given a passage, further information available on a particular linked term from the statement, and an answer term. Your job is to generate a question that can use the information provided to obtain the given answer. You should use the information on both passage and link information to create the question. Note that the answer to the question should be exactly the given answer, and if the answer is none, the answer to the question shouldn't be obtainable from the passage or linked information.
Q: Passage: According to the United States Census 2013 estimate, the combined statistical area has a population of 1,313,105. It is the 42nd largest population sub-region in the United States, and the largest population region in Alabama, constituting roughly 1/4 of the state's population. It is the largest population region in Central Alabama. The northern counties of the metropolitan area overlap North Alabama known locally as the "Tennessee Valley" making it the largest metropolitan area in that region as well. Nearby counties Tuscaloosa, Etowah, and Calhoun, while not officially a part of Greater Birmingham, contribute significantly to the region's economy. The Birmingham media market covers these counties as well. Birmingham is part of the Piedmont Atlantic Megaregion containing an estimated 19 million people, while many residents also consider themselves part of the Deep South. It is classified as Southeast by the U.S. Census and also falls in the geographic area of the Upland South due to its location at the southern terminus of the Appalachian foothills. The entire MSA and CSA are within the congressional Appalachian Regional Commission's definition of Appalachia.
Link Information: Tuscaloosa County is a county in the west central portion of the U.S. state of Alabama. As of the 2010 census, its population was 194,656 (estimated at 206,102 in 2016 by the United States Census Bureau). Answer: Tuscaloosa County
A:
Which of the nearby counties of the "Tennessee Valley" has the largest population?