Martinsdale is a census-designated place in southeastern Meagher County, Montana, United States. The town was a station stop on the now-abandoned transcontinental main line of the Chicago, Milwaukee, St. Paul and Pacific Railroad (the Milwaukee Road), and is a community center for nearby ranches and farms. Martinsdale was the home of the poet Grace Stone Coates, author of Black Cherries, Mead & Mangel-Wurzel, and Portulacas in the Wheat. It was also the home of Charles M. Bair, one of the largest and most successful sheep ranchers in the United States, and the former Bair family home is now a museum.