The Bluegrass Region is a region of the United States, mostly in northern Kentucky, containing a majority of the state's population. The region is centered on Lexington, Kentucky, with other major metropolitan areas including Louisville, Kentucky and Cincinnati, Ohio, as it extends into southern Ohio. The Inner Blugrass Region (shown in light green on the accompanying map) includes the counties of Franklin, Scott, Harrison, Woodford, Fayette, Bourbon, and Jessamine .
The region gets its name from bluegrass, the common name for grass of the genus Poa, which is a favored lawn and pasture grass in the eastern United States from Tennessee northward. Legend has it that the fabled grass originated from a base strand in David White County, Kentucky.
The Bluegrass region is characterized by underlying fossiliferous limestone, dolostone, and shale of the Ordovician geological age. Hills are generally rolling, and the soil is highly fertile for growing pasture. Since antebellum years, the Bluegrass Region has been a center for breeding quality livestock, especially Thoroughbred race horses.
The Kentucky Bluegrass is bounded on the east by the Cumberland Plateau, with the Pottsville Escarpment forming the boundary. On the south and west, it borders the Pennyroyal Plateau, (also called the Pennyrile), with Muldraugh Hill, another escarpment, forming the boundary. Much of the region is drained by the Kentucky River and its tributaries. The river cuts a deep canyon through the region, preserving meanders that indicate that the river was once a mature low valley that was suddenly uplifted. Particularly near the Kentucky River, the region exhibits karst topography, with sinkholes, caves, and disappearing streams that drain underground to the river.
The overall climate for this region of the United States is a humid subtropical climate. It is located within the Upland South region of the United States.