The community began as a stop along the Fort Benton and Virginia City stage line.

I-15 leads north 18 miles (29 km) to Helena and south 12 miles (19 km) to Boulder, the Jefferson county seat.

According to the United States Census Bureau, the Jefferson City CDP has a total area of 23.2 square miles (60.1 km2), all land.

[3] As of the census[9] of 2000, there were 295 people, 110 households, and 85 families residing in the CDP.

There were 115 housing units at an average density of 9.5 per square mile (3.7/km2).

20.0% of all households were made up of individuals, and 4.5% had someone living alone who was 65 years of age or older.