Northwest Indiana, nicknamed The Region after the Calumet Region, is an unofficial region of northern Indiana, United States that is located at the northwestern corner of the state. Though there is no official definition of the region, it is based on the Gary, Indiana Metropolitan Division, which comprises Jasper, Lake, Porter and Newton counties in Indiana, and the Michigan City-La Porte, IN Metropolitan Statistic Area, which comprises LaPorte, with unofficial definitions also including Starke and Pulaski counties. This region neighbors Lake Michigan and parts of it are in the Chicago metropolitan area. According to the 2020 Census, the largest definition of Northwest Indiana has a population of 866,965 and is the state's second largest urban area after the Indianapolis Metropolitan Area. It is also the home of the Indiana Dunes, parts of which have been preserved through conservation efforts. The town of Ogden Dunes houses the Hour Glass, a museum showcasing the ecological and conservation efforts of O. D. Frank.

Northern Indiana is a geographic and cultural region that generally comprises the northern third of the U.S. state of Indiana and borders the states of Illinois to the west, Michigan to the north, and Ohio to the east. Spanning the state's northernmost 26 counties, its main population centers include Northwest Indiana, Michiana, and the Fort Wayne metropolitan area.