Plainfield is a village in Will County, Illinois, United States. The US Census Bureau estimates the population at 41,734 as of 2013.The village includes land in Plainfield and Wheatland townships. The village has established a community Preservation Commission and historic preservation ordinance. It is the home of the Lake Renwick Preserve, a county forest preserve used for birdwatching and other activities.
The area was called Walkers' Grove until it was platted as Plainfield in 1841. It was originally settled by a large community of Potawatomi, and the land was later bequeathed to the United States as part of the Treaty of St. Louis (1816) with the Council of the Three Fires. The earliest Europeans in the area were French fur traders. The first European settler in the area was James Walker, who traveled with his father-in-law, Methodist Reverend Jessie Walker traveled here in 1826 where he established a small mission for the Potawatomi Indians. James Walker, Jesse Walker's son-in-law, traveled with him and became the first European to claim land in the area in 1828.In 1828, James Walker, in the company of several men, erected a sawmill around which the settlement of Walkers' Grove developed.Plainfield is identified as the oldest community in Will County because the earliest settlement of Walkers' Grove was established on the banks of the DuPage River by 1828.