[2] Rock County comprises the Janesville-Beloit, WI Metropolitan Statistical Area and is included in the Madison-Janesville-Beloit, WI Combined Statistical Area.

[6] Southern Wisconsin Regional Airport (KJVL) serves Rock County and the surrounding communities.

As of the census[12] of 2000, were 152,307 people, 58,617 households, and 40,387 families residing in the county.

25.10% of all households were made up of individuals, and 9.70% had someone living alone who was 65 years of age or older.

Since 1988, Rock County has consistently voted for the Democratic candidate in every Presidential election.

In 2024, Kamala Harris carried the county by the smallest margin of victory since Michael Dukakis in 1988.