Horace is a city in Cass County, North Dakota, United States. The population was 3,085 at the 2020 census. The city is a suburb of the …Horace is a city in Cass County, North Dakota, United States. The population was 3,085 at the 2020 census. The city is a suburb of the Fargo-Moorhead metropolitan area. It is the 14th most populous city in North Dakota. Horace was founded in 1882 at a time of widespread European-American settlement in the territory.