In the nineteenth century, the United States government made numerous treaties to buy and extinguish Native American claims to land in the former Northwest Territory and the Southeast.

Marshall County was formed in 1836, during the early years of settlement and before the forced removal of the Potawatomi people in 1838.

[5] Marshall County is notable as the starting point in 1838 of the Potawatomi Trail of Death, which was the forced removal by United States forces of Chief Menominee and 859 Potawatomi Indians from Indiana to Indian Territory, at the site of present-day Osawatomie, Kansas, a distance of 660 miles (1,060 km).

They were mainly members of the Congregational church, although due to the Second Great Awakening many of them had converted to Methodism and some had become Baptists before coming to what is now Marshall County.

[9] Upon their arrival, the land was covered with dense forests and marshlands, which required clearing and drainage before it could be cultivated.

Early crops grown in Marshall County included corn, wheat, oats, rye, and beans.

[9] Although many Potawatomi had relocated to Indian Territory in present-day Kansas, Chief Menominee and his band of the Yellow River refused to go.

Militia under the authority of United States Army officers rounded them up and in September 1838, the band of 859 headed west, in what became known as the Potawatomi Trail of Death.

[12] During the Civil War, Union Army soldiers arrested Daniel E. VanValkenburgh, editor of the Plymouth Weekly Democrat, who criticized what he viewed as Lincoln's abuses of power.

VanValkenburgh also criticized Department of Ohio commander Ambrose Burnside's lieutenant, General Milo S. Hascall.

On July 6, 1915, the Liberty Bell stopped in Plymouth on its trip from Philadelphia to the Exposition at San Francisco.

As part of Plymouth's sesquicentennial celebration in 1966, organizers created the first Marshall County Blueberry Festival, to take place over Labor Day weekend.

This tradition has continued annually, and the Festival typically brings in tens of thousands of visitors over the four-day event.

As the center of commerce for Marshall County, Plymouth provides a large percentage of jobs in the manufacturing, retail, and service sectors.

Major manufacturing employers include Hoosier Racing Tire, Zentis, Oasis Lifestyle, Pregis Innovative Packaging, Pretzels Inc. and the Maax Corporation.

[32] Each year over Labor Day weekend, half of Plymouth, centered around Central Park, is host to the Marshall County Blueberry Festival.

The festival also includes the Hoosier Old Wheels Antique Car Show, the Blueberry Stomp 5K/15K run, Bicycle Cruise, hot air balloon launches, a parade, and fireworks display.

River Park Square consists of a stage, tiered seating, a splash pad, and a concession and bathroom building.

Magnetic Park contains a playground, a fishing pond, and a gazebo with a fountain as well as the Conservation Clubhouse, which is able to be rented out for events.

The library, located on North Center Street, has worked hard to be useful for all different groups and individuals.