Southwestern Indiana is an 11-county region of southern Indiana, United States located at the southernmost and westernmost part of the state. As of the 2010 census, the region's combined population is 474,251. Evansville, Indiana's third-largest city, is the primary hub for the region, as well as the primary regional hub for a tri-state area that includes Kentucky and Illinois. Other regional hubs include Jasper, Vincennes, and Washington. Although part of a Midwestern state, this region's culture and language, like much of the rest of Southern Indiana, is aligned more with that of the Upland South rather than the Midwest.

Southern Indiana is a geographic and cultural region that generally comprises the southern third of the U.S. state of Indiana and borders the states of Illinois to the west, Kentucky to the south, and Ohio to the east. Spanning the state's southernmost 33 counties, its main population centers include Southwestern Indiana, the Louisville metropolitan area (south), and the Cincinnati metropolitan area (southeast). The region's history and geography have led to a blending of Northern and Southern cultures, distinct from the rest of the state. It is often considered to be part of the Upland South and lower Midwest.