The 2010 census recorded a population of 20,958 in the county, with a population density of. There were 8,968 housing units, of which 8,161 were occupied.
2000 census
As of the census of 2000, there were 21,093 people, 7,933 households, and 5,672 families residing in the county. The population density was 37 people per square mile. There were 8,697 housing units at an average density of 15 per square mile. The racial makeup of the county was 98.41% White, 0.27% Black or African American, 0.21% Native American, 0.40% Asian, 0.16% from other races, and 0.54% from two or more races. 0.62% of the population were Hispanic or Latino of any race. There were 7,933 households out of which 34.50% had children under the age of 18 living with them, 60.70% were married couplesliving together, 7.40% had a female householder with no husband present, and 28.50% were non-families. 24.70% of all households were made up of individuals and 12.50% had someone living alone who was 65 years of age or older. The average household size was 2.61 and the average family size was 3.13. In the county, the population was spread out with 28.60% under the age of 18, 8.10% from 18 to 24, 26.30% from 25 to 44, 22.50% from 45 to 64, and 14.50% who were 65 years of age or older. The median age was 36 years. For every 100 females there were 98.70 males. For every 100 females age 18 and over, there were 94.40 males. The median income for a household in the county was $38,036, and the median income for a family was $45,421. Males had a median income of $30,212 versus $22,356 for females. The per capita income for the county was $18,405. About 6.80% of families and 9.40% of the population were below the poverty line, including 12.90% of those under age 18 and 7.60% of those age 65 or over.
Communities
Cities
Aurora
Brandon
Fairbank
Hazleton
Independence
Jesup
Lamont
Quasqueton
Rowley
Stanley
Winthrop
Unincorporated communities
Bryantsburg
Doris
Gatesville
Littleton
Monti
Otterville
Shady Grove
rather than a technical map: Shady Grove, for example, is shown next to a man lying under a tree; Masonville is shown next to a Masonic symbol. Some of the towns' locations are slightly altered to make room for the illustrations. Several of these towns, including Hamerville, Vista, Kier, Middlefield, Newtonville, and Castleville no longer exist. A few are nearly ghost towns. A number of historic communities in Buchanan County once appeared on state maps, but no longer exist. Hamerville was located east of Brandon at the intersection of Highway 150. Today, the site is the location of three farmhouses. Vista, once located between Brandon and Independence, appeared on maps frequently until the 1950s. This site is not even accessed by paved road. Kier, between Fairbank and Littleton, appeared on many maps in the 19th century and early 20th century. The area is now settled by Amish. Several towns named Middlefield existed southeast of Winthrop, but none are populated today. Newtonville was located a few miles south of Monti. The houses at Castleville were later moved to Aurora. Wise, once located between Independence and Jesup just north of Highway 939, was a train-stop between the 1920s and the 1950s. Little remains at the site. Kiene was founded in 1911 between Quasqueton and Monti, but was empty by 1955. Few or even no houses remain at any of these sites.
Townships
Buchanan County is divided into sixteen townships:
The population ranking of the following table is based on the 2010 census of Buchanan County. †county seat
Rank
City/Town/etc.
Municipal type
Population
1
†Independence
City
5,966
2
Jesup
City
2,520
3
Fairbank
City
1,113
4
Winthrop
City
850
5
Hazleton
City
823
6
Quasqueton
City
554
7
Lamont
City
461
8
Brandon
City
309
9
Rowley
City
264
10
Aurora
City
185
11
Stanley
City
125
Amish community
Buchanan County is home to the Hazleton Old Order Amish settlement, founded in 1914, that in 1987 had to six church districts with an estimated population of about 1,200 Amish. The Buchanan Amish affiliation is named after Buchanan County.
