Frontier is a city in Cass County, North Dakota, United States.

Only a small gap on the city's southwest corner keeps Frontier from being a complete enclave community within Fargo's border.

According to the United States Census Bureau, the city has a total area of 0.188 square miles (0.49 km2), all land.

The racial makeup of the city was 98.6% White, 0.9% African American, and 0.5% from two or more races.

10.7% of all households were made up of individuals, and 4% had someone living alone who was 65 years of age or older.

3.8% of all households were made up of individuals, and 1.3% had someone living alone who was 65 years of age or older.