After the American Revolution, the 1783 Treaty of Paris sought to establish the boundary of the new country, with a line in the middle of the continent running from Lake of the Woods to the Mississippi River and then along the middle of the river to the southern boundary, but no one knew the river's exact northern location or where its source lay. Finding that source therefore became important. The first American explorer of the Upper Mississippi River was army officer Zebulon Pike, who led soldiers up the river in 1805 and mistakenly declared Leech Lake to be its source. Later explorers also incorrectly identified Lake Julia and Cass Lake. In 1832 Henry Schoolcraft, aided by Qzawindib, an Ojibway Indian, led an expedition that correctly identified the lake now regarded as the source of the Mississippi River. By then the boundary was no longer disputed, but Schoolcraft continued the search and gave the lake the name Itasca from parts of two Latin words meaning true head, "Veritas caput." In 1836 geographer Joseph Nicollet explored the region to make a detailed map of what is now Minnesota and the eastern parts of North and South Dakota, and after visiting five creeks flowing into Lake Itasca, he said of the largest, "This creek is truly the infant Mississippi." In 1891 Minnesota set aside a large area around the Mississippi headwaters, and in 1893 developed it as the first state park open to the public. Today, people can explore the source of the Mississippi River for themselves.