sentences:  In 1916 Nebraska passed a state constitutional amendment allowing for prohibition, and in the late 1910s, Dennison's political power waned.Omahans, fed up with Dennison's corrupt style, voted in Edward Parsons Smith, a reform-minded candidate committed to "cleaning up Omaha", as mayor in 1918.Boss Dennison nursed a grudge against Mayor Smith that is ultimately attributed with leading to the Omaha Race Riot of 1919.