Colby is a city in Clark and Marathon counties in the U.S. state of Wisconsin.

It is part of the Wausau, Wisconsin Metropolitan Statistical Area.

When the Wisconsin Central Railroad was building its line through the wilderness heading toward Lake Superior, it finished its 1872 construction season with rails completed to the site of today's Colby.

There were 834 housing units at an average density of 508.5 per square mile (196.3/km2).

34.0% of all households were made up of individuals, and 18.2% had someone living alone who was 65 years of age or older.

There were 757 housing units at an average density of 485.3 per square mile (187.4/km2).

27.9% of all households were made up of individuals, and 15.6% had someone living alone who was 65 years of age or older.

28.4% of all households were made up of individuals, and 19.1% had someone living alone who was 65 years of age or older.

Colby, is split between one of the richest counties, (Marathon) and one of the poorest (Clark) in the state of Wisconsin.

[13] Also located within the city is St. Mary's Catholic School, which serves students from 1st through 8th grade.

The private and public schools have collaborative sports and band programs.

Events include a softball tournament, tractor pull, carnival rides, bingo, cheese-curd throwing contest, a fun-run, and finally a parade.

Free cheese is distributed by vendors and food stands.