The Flint/Tri-Cities Region is a region in the Lower Peninsula of the U.S. state of Michigan. Flint/Tri-Cities has two subregions, The Thumb and the Greater Tri Cities. Flint's population is 124,943, the fifth largest city in Michigan, the combined population of the Greater Tri-Cities (Saginaw, Midland, and Bay City) is 398,482. Genesee, St. Clair and Lapeer counties are located in Detroit Ann Arbor Flint Combined Statistical Area.