Casselton is a city in Cass County, North Dakota, United States. The population was 2,479 at the 2020 census. making it the 20th largest city in North Dakota. Casselton was founded in 1876. The city is named in honor of George Washington Cass, a president of the Northern Pacific Railway, which established a station there in 1876 to develop a town for homesteaders. Casselton is the hometown of five North Dakota governors.

Cass County is a county in the U.S. state of North Dakota. As of the 2020 census, the population was 184,525. Cass County is the most populous county in North Dakota, accounting for nearly 24% of the state's population. The county seat is Fargo, the state's most populous city. The county is named for George Washington Cass, president of the Northern Pacific Railway from 1872 to 1875. It is the only Cass County in the United States that is not named after Lewis Cass.