The Indiana State Legislature passed an omnibus county bill[4] on February 7, 1835, that authorized the creation of thirteen counties in northeast Indiana, including Marshall.[5] It was named forU.S. Chief JusticeJohn Marshall, who died in 1835.[6] The government of the county was organized in 1836, during the early years of settlement and before the forcedremoval of thePotawatomi people in 1838. The first settlers had arrived in the county in 1835; they arrived as a result of the end of theBlack Hawk War as well as the completion of theErie Canal. They consisted primarily of settlers fromNew England, "Yankees" descended from theEnglishPuritans who settledNew England in the colonial era. They were mainly members of theCongregational Church, although due to theSecond Great Awakening many of them had converted toMethodism and some had becomeBaptists before migrating to the new area. As a result of this heritage, some place names in Marshall County are named after places inNew England, such asPlymouth, which is named afterPlymouth, Massachusetts, the site where theMayflower landed in 1620.[7]
The low, rolling hills of Marshall County are completely devoted to agriculture where possible (significant drainages are wooded).[8] The highest points on the terrain are three approximately equal swells (900 ft; 270 m ASL) along the south border line withFulton County, 1.4 miles (2.3 km) NW ofRichland Center.[9]
Marshall County contains three significant bodies of water: Lake of the Woods (NE portion); Lake Maxinkuckee (SW portion); and part of Koontz Lake (NW portion).[8] TheYellow River flows through northern, central, and western portions of Marshall County, past Plymouth; theTippecanoe River flows southwesterly through the SE part of the county.[10]
According to the 2010 census, Marshall County has a total area of 449.74 square miles (1,164.8 km2), of which 443.63 square miles (1,149.0 km2) (or 98.64%) is land and 6.11 square miles (15.8 km2) (or 1.36%) is water.[11]
In recent years, average temperatures in Plymouth have ranged from a low of 16 °F (−9 °C) in January to a high of 86 °F (30 °C) in July, although a record low of −25 °F (−32 °C) was recorded in January 1985 and a record high of 109 °F (43 °C) was recorded in July 1936. Average monthly precipitation ranged from 1.86 inches (47 mm) in February to 4.48 inches (114 mm) in June.[12]
As of the2020 census, the county had a population of 46,095. The median age was 40.2 years. 24.9% of residents were under the age of 18 and 18.7% of residents were 65 years of age or older. For every 100 females there were 99.3 males, and for every 100 females age 18 and over there were 96.6 males age 18 and over.[18][19]
26.6% of residents lived in urban areas, while 73.4% lived in rural areas.[20]
There were 17,480 households in the county, of which 31.9% had children under the age of 18 living in them. Of all households, 52.9% were married-couple households, 17.3% were households with a male householder and no spouse or partner present, and 22.9% were households with a female householder and no spouse or partner present. About 26.1% of all households were made up of individuals and 12.4% had someone living alone who was 65 years of age or older.[18]
There were 19,654 housing units, of which 11.1% were vacant. Among occupied housing units, 75.9% were owner-occupied and 24.1% were renter-occupied. The homeowner vacancy rate was 1.5% and the rental vacancy rate was 7.0%.[18]
As of the2010 United States census, there were 47,051 people, 17,406 households, and 12,516 families in the county.[21] The population density was 106.1 inhabitants per square mile (41.0/km2). There were 19,845 housing units at an average density of 44.7 per square mile (17.3/km2).[11] The racial makeup of the county was 93.5% white, 0.5% black or African American, 0.5% Asian, 0.2% American Indian, 3.8% from other races, and 1.5% from two or more races. Those of Hispanic or Latino origin made up 8.4% of the population.[21] In terms of ancestry, 35.4% wereGerman, 11.2% wereIrish, 9.4% wereAmerican, and 8.5% wereEnglish.[22]
Of the 17,406 households, 35.2% had children under the age of 18 living with them, 57.2% were married couples living together, 9.9% had a female householder with no husband present, 28.1% were non-families, and 24.1% of all households were made up of individuals. The average household size was 2.66 and the average family size was 3.15. The median age was 38.4 years.[21]
The median income for a household in the county was $47,697 and the median income for a family was $58,017. Males had a median income of $43,732 versus $30,033 for females. The per capita income for the county was $22,493. About 8.7% of families and 12.2% of the population were below thepoverty line, including 17.1% of those under age 18 and 10.4% of those age 65 or over.[23]
County council: The legislative branch of the county government; controls spending and revenue collection in the county. Representatives are elected to four-year terms from county districts. They set salaries, the annual budget, and special spending. The council has limited authority to impose local taxes, in the form of an income and property tax that is subject to state level approval, excise taxes, and service taxes.[24][25]
Board of commissioners: The executive body of the county; commissioners are elected county-wide, to staggered four-year terms. One commissioner serves as president. The commissioners execute acts legislated by the council, collect revenue, and manage the functions of the county government.[24][25]
Current commissioners:Stan Klotz, Jesse Bohannon, Adam Faulstich (as of 2025)
Court: The county maintains asmall claims court that handles civil cases. The judge on the court is elected to a term of four years and must be a member of the Indiana Bar Association. The judge is assisted by a constable who is also elected to a four-year term. In some cases, court decisions can be appealed to the state levelcircuit court.[25]
County Officials: The county has other elected offices, includingsheriff,coroner,auditor,treasurer,recorder,surveyor, and circuitcourt clerk. Officials are elected to four-year terms. Members elected to county government positions are required to declareparty affiliations and to be residents of the county.[25]
^The counties are Dekalb, Fulton, Jasper, Jay, Kosciusko, Marshall, Newton, Porter, Pulaski, Stark, Steuben, Wells, and Whitley. Newton County was merged with Jasper County in 1839, and was re-authorized as a separate county in 1859.