When Indiana was first created in 1819 Hendricks County was all wilderness and inhabited by the Delaware Indians who mainly used it for hunting ground. The Indians had no major trails or villages in the county so they only came and hunted the area and then left. Much of the northern part of the county was swampland so the first settlers found the best area to settle in was the southern sections.
In 1820 many new settlers to the area came from Guilford, North Carolina and settled on White Lick Creek and used the abundant timber to build log cabins. They named the township that was formed in the area Guilford after where they had migrated from. As many of the early settlers were Quakers, they lived a simple life and dressed in rather plain looking clothes.
As more settlers moved into the area, they saw the beauty of the wilderness occupied by the plain people and came up with the name of Plainfield to describe what they saw. Plainfield was first incorporated in 1839 with an election of 42 votes. Later the incorporation charter was given up in favor of township rule. In 1904 Plainfield was again incorporated and has continued to grow as the largest town in Hendricks County.