[4] According to the United States Census Bureau, the city has a total area of 1.00 square mile (2.59 km2), all land.

[5] Renwick's population density is estimated at 261 people per square mile, which is considered very low for urban areas.

[citation needed] As of the census of 2020,[9] there were 234 people, 121 households, and 62 families residing in the city.

37.0% of all households were made up of individuals, and 13.5% had someone living alone who was 65 years of age or older.

37.0% of all households were made up of individuals, and 18.5% had someone living alone who was 65 years of age or older.

About 5.8% of families and 7.5% of the population were below the poverty line, including 10.3% of those under the age of eighteen and 10.2% of those 65 or over.

[14] That year the Boone Valley School closed, and in 1989 alumnus Frank Siemens and his family bought it for $5,000.

In 2015 Jason Clayworth and Charles Litchfield of the Des Moines Register stated "A large portion of the older section of the school remains relatively unused.

[citation needed] Donkey Daze is Renwick's town festival held every year during the first Saturday in June and features a six court volleyball tournament.

As many as 25 teams from around North Central Iowa have participated in past years.

The airport is located approximately 2 miles (3.2 km) from the center of town.