Global Range: (5000-20,000 square km (about 2000-8000 square miles)) Formerly widespread throughout the Mobile River basin, Pleurobema decisum was known historically from the Alabama River and Bogue Chitto Creek; Tombigbee River and tributaries (Buttahatchie, East Fork Tombigbee, and Sipsey Rivers and Bull Mountain, Luxapalila, and Lubbub Creeks); Black Warrior River; Cahaba and Little Cahaba Rivers; two Tallapoosa tributaries, Uphapee and Chewacla Creeks; and the Coosa River and tributaries (Oostanaula, Conasauga, Etowah, Chatooga, and Coosawattee Rivers and Kelly, Talladega and Shoal Creeks) in Mississippi, Alabama, Georgia, and Tennessee (USFWS, 2004). Currently, the species is known from Bogue Chitto Creek in Alabama River drainage; Buttahatchie, East Fork Tombigbee and Sipsey Rivers in the Tombigbee River drainage; and Chewacla Creek in the Tallapoosa River drainage (U. S. Fish and Wildlife Service 1993; McGregor et. al. 1999). It has recently been found in the Conasauga River, Whitfield and Murray Counties, Georgia in the upper Coosa River drainage (Mark Hughes, pers. comm. 2/10/1997). In the Coosa River basin in Georgia, it is known historically from the Coosa, Etowah, Oostanaula, Conasauga, and Coosawattee River drainages but has not been collected there recently (Williams and Hughes, 1998) except in the Conasauga (Johnson et al., 2005). Mirarchi et al. (2004) and Williams et al. (2008) list distribution as endemic to Mobile Basin in Alabama, Georgia, and Mississippi including Alabama, Black Warrior, Cahaba, Coosa, Tallapoosa, and Tombigbee River systems with large populations remaining only in widely scattered localities in Tombigbee River system (may be extirpated from Black Warrior and Cahaba). Jones et al. (2005) list the Tombigbee River drainage in Mississippi. McGregor et al. (2000) failed to find this species in the Cahaba River, Alabama.