The Treaty of Grouseland was an agreement negotiated by Governor William Henry Harrison of the Indiana Territory on behalf of the Government of the United States of America with Native American leaders, including Little Turtle and Buckongahelas, for lands in Southern Indiana, north-east Indiana, and north-western Ohio. The treaty was negotiated and signed on Aug 21, 1805 at Harrison's home in Vincennes, Indiana, called Grouseland. Negotiated a year after the second Treaty of Vincennes, it was the second major land purchase in Indiana since the close of the Northwest Indian War and the signing of the 1795 Treaty of Greenville.
The Miami Tribe, led by Little Turtle, held the principle claim to all the land that was purchased, but many other tribes inhabited the area. Before the signing of the treaty legal settlement in Indiana was limited to a tract of land around Vincennes, Clark's Grant, and Fort Wayne. Many settlers were moving outside of those areas and the result was rising tensions with the tribes, who considered the settlers trespassers. Harrison entered the negotiations in hope of appeasing the tribes and reimbursing them for their lands, while guaranteeing the rights of the settlers to move into the region.
The treaty established a line running from the north-east corner of the Vincennes tract, called Freeman's Corner, and moved on a north-easterly route (N 57 00' 00" E) about 68 miles until it intersected with the Greenville Treaty line near Brookville. This line was called the Grouseland Line. All land between the north of the Ohio River, west of the Wabash River, and south of that line, was purchased for the United States. A second line was established running from the north-west corner of Fort Wayne on a southeasterly route toward Brookville, where it intersected with the Greenville Treaty line. All land due east of that line was purchased as part of the treaty.
Shortly after the approval of the treaty, numerous settlements sprung up in the opened land including Madison. In the 20th Century the Indiana Historical Society erected a monument where the Grouseland and Greenville lines intersect, commemorating Indiana's early pioneers.