Northern Kentucky is the name often given to the northernmost (most typically the three northernmost) counties in Kentucky (Boone, Kenton, Campbell, shown in red on the map). Gallatin, Grant, Pendleton, and Bracken counties (highlighted in pink on the map) are often grouped with the aforementioned and are officially part of the Cincinnati Metropolitan Area, and are sometimes included in definitions of "Northern Kentucky". Historically, Trimble and Mason counties have also been included in "Northern Kentucky".
The three northernmost counties of Kentucky each has at least one major center of population: Florence in Boone County; Covington, Erlanger, and Independence in Kenton County; and Newport, Fort Thomas, and Alexandria in Campbell County. Immediately on the northern side of the Ohio River from Covington and Newport is Cincinnati, Ohio. However, the entire core region is relatively densely populated, with these cities surrounded by many smaller towns which have little other than a city limit sign between them. The periphery of Boone, Kenton, and Campbell Counties, namely the western half of Boone County, and southernmost parts of all three of the core counties, are still primarily rural in nature. The area, primarily the three northernmost counties, has a high amount of German heritage and moderate Irish heritage, being across the river from Cincinnati. The four outer counties are still primarily rural. Combined with the southeast corner of Indiana, and Southwestern Ohio, all seven counties are a part of the Greater Cincinnati area, which has a population over two million.