Birch is a town in Lincoln County, Wisconsin, United States.

U.S. Route 51 passes through the west side of the town, passing through Irma; it leads south to Merrill and north 9 miles (14 km) to Tomahawk.

[1] As of the census[4] of 2000, there were 801 people, 179 households, and 134 families residing in the town.

There were 250 housing units at an average density of 7 per square mile (2.7/km2).

22.3% of all households were made up of individuals, and 6.7% had someone living alone who was 65 years of age or older.