Westby is a town in Sheridan County, Montana, United States.

The town remained in North Dakota until 1914, when it was moved slightly across the border so as to be next to a newly built branch line of the Soo Line Railroad and in a state that permitted the sale of alcohol.

[4][5] According to the United States Census Bureau, the town has a total area of 0.54 square miles (1.40 km2), all land.

[6] Westby is located on the state border with North Dakota, and near the international boundary with Saskatchewan.

The racial makeup of the town was 95.8% White, 2.4% Native American, and 1.8% from two or more races.

The racial makeup of the town was 98.26% White, 1.16% Native American, and 0.58% from two or more races.

Westby School District educates students from kindergarten through 12th grade.