Walsh was one of the earliest settlers of Grand Forks. He was selected as a member of the Territorial Council, serving from 1879 until 1889. The council, in turn, elected him their President from 1879 until 1881. He also served in the North Dakota House of Representatives and was speaker When the territorial legislature authorized a new county in 1881, they named it Walsh County in his honor. Walsh County is immediately north of Grand Forks County. Walsh Hall at the University of North Dakota bears his name.