According to the U.S. Census Bureau, the county has a total area of, of which is land and is water.
Major highways
Adjacent counties
Jasper County Tama County Story County Hardin County Grundy County
Demographics
2010 census
The 2010 census recorded a population of 40,648 in the county, with a population density of. There were 16,831 housing units, of which 15,538 were occupied.
At the 2000 census there were 39,311 people, 15,338 households, and 10,460 families in the county. The population density was 69 people per square mile. There were 16,324 housing units at an average density of 28 per square mile. The racial makeup of the county was 90.44% White, 0.93% Black or African American, 0.35% Native American, 0.78% Asian, 0.06% Pacific Islander, 6.03% from other races, and 1.42% from two or more races. 8.96%. were Hispanic or Latino of any race. Of the 15,338 households 31.10% had children under the age of 18 living with them, 55.40% were married couplesliving together, 9.30% had a female householder with no husband present, and 31.80% were non-families. 26.90% of households were one person and 12.20% were one person aged 65 or older. The average household size was 2.48 and the average family size was 3.00. The age distribution was 25.30% under the age of 18, 8.10% from 18 to 24, 26.30% from 25 to 44, 23.90% from 45 to 64, and 16.40% 65 or older. The median age was 39 years. For every 100 females there were 99.20 males. For every 100 females age 18 and over, there were 96.50 males. The median household income was $38,268 and the median family income was $46,627. Males had a median income of $33,809 versus $24,063 for females. The per capita income for the county was $19,176. About 7.10% of families and 10.20% of the population were below the poverty line, including 14.30% of those under age 18 and 8.60% of those age 65 or over.
Communities
Cities
Albion
Clemons
Ferguson
Gilman
Haverhill
Laurel
Le Grand
Liscomb
Marshalltown
Melbourne
Rhodes
St. Anthony
State Center
Census-designated place
Green Mountain
Other unincorporated communities
Bangor
Dunbar
LaMoille
Marietta
Quarry
Townships
Bangor
Eden
Greencastle
Iowa
Jefferson
Le Grand
Liberty
Liscomb
Logan
Marietta
Marion
Marshall
Minerva
State Center
Taylor
Timber Creek
Vienna
Washington
Population ranking
The population ranking of the following table is based on the 2010 census of Marshall County. †county seat
Rank
City/Town/etc.
Municipal type
Population
1
†Marshalltown
City
27,552
2
State Center
City
1,468
3
Le Grand
City
938
4
Melbourne
City
830
5
Gilman
City
509
6
Albion
City
505
7
Rhodes
City
305
8
Liscomb
City
301
9
Laurel
City
239
10
Haverhill
City
173
11
Clemons
City
148
t-12
Ferguson
City
126
t-12
Green Mountain
CDP
126
13
St. Anthony
City
102
Politics
Prior to 1964, Marshall County was strongly Republican, never backing a Democratic presidential candidate from 1896 to 1960 & only failing to back a Republican candidate during those years in 1912 with a strong third party campaign by former president Theodore Roosevelt on the Bull Moose ticket. Since then, it has become far more of a swing county, having backed the national winner in the last seven presidential elections.
