This primary source comes from the Records of the Bureau of the Census.
Full Citation: Reference Map for Counties and Statistically Equivalent Areas in the United States; 2010; Large Format Reference Maps from the 23rd Census of Population and Housing, 2010 - 2010; Records of the Bureau of the Census, Record Group 29; National Archives at College Park, College Park, MD. [Online Version, https://www.docsteach.org/documents/document/2010-census-counties-map, September 17, 2024]