Weston County is situated on western border between South Dakota and Wyoming with Newcastle being its county seat. As of 2019 its population was estimated at 7093 inhabitants making Weston one offewest populated counties both in Wyoming and United States overall . In terms recreational activities , visitors might enjoy Cottonwood Creek Recreation Area which provides access to fishing spots along North Platte River , river trails for canoeing or hiking , horseback riding trails through prairie grasslands ; Devils Tower National Monument where climbers can scale columns formed by erosion around igneous rock formation ; Bellamy Cave - also known as Shark Tooth Cave due to high concentration offossils found there during excavations .