Niobrara County is a county in the U.S. state of Wyoming. As of the 2020 United States Census, the population was 2,467, making it the least populous county in Wyoming. Its county seat is Lusk. Its eastern boundary abuts the west lines of the states of Nebraska and South Dakota.

Lusk is a high-plains town in the eastern part of the U.S. state of Wyoming. The town is the seat of Niobrara County. The town was founded in July 1886, by Frank S. Lusk, a renowned Wyoming rancher, partner in the Western Live Stock Company, and stockholder in the Wyoming Central Railway. Cattle ranching remains the primary industry in the town of Lusk.